Silver nanoprisms grown into structural colors by high power LEDs

How to chemically synthesize silver nanoparticles, then grow them into triangular nanoprisms with light from a variety of LEDs. Each color LED creates a different size nanoprism, which has its own characteristic color.
CMDITR video: • Silver Nanoprisms Synt...
Multispectral LED driver on Github: github.com/benkrasnow/MultiSp...
Chemicals sourced from Amazon/eBay
LR-1 spectrometer: www.aseq-instruments.com/LR1....
Micropipette set: www.amazon.com/gp/product/B06... www.amazon.com/gp/product/B01...
20ml glass vials with PTFE lined cap (do not use metal-lined): Environmental Express APC1675P Already gone from Amazon
pH pen (this cost more than I remember, but it works really well, and has lasted many years. Cheaper pH pens are often pretty bad) www.amazon.com/gp/product/B01...
Comparison of CD, DVD, Blu-ray discs with electron microscope:
/ 615327472909840385
Great way to find related papers:
www.connectedpapers.com/
Research sources:
• Silver Nanoprisms Synt...
sci-hub.se/doi.org/10...
sci-hub.se/10.1038/nature01937
sci-hub.se/10.1126/science.10...
sci-hub.se/10.1002/smll.20080...
sci-hub.se/10.1039/b302943c
opg.optica.org/oe/fulltext.cf...
www.rsc.org/suppdata/nr/c4/c4...
sci-hub.se/10.1039/C4NR06901C
sci-hub.se/10.1155/2018/1781389
www.cytodiagnostics.com/pages...
Support Applied Science on Patreon: / appliedscience

[@ThisOldTony]

the projects you come up with never cease to amaze me. great work!

[@Ektachris]

You might have missed it but he spelt “subscribe” in nano silver particles.

[@UberAlphaSirus]

MUM! It's that time traveler again!

[@customsolutionsinc]

I follow you both.... Very interest stuff and approach.

[@silasmarrs1409]

A collaboration between you two would be epic.

[@eamonia]

No way! That's too cool, man.

[@Nighthawkinlight]

Oh no. I have a centrifuge in shipping right now that I bought for dewatering nano particles. I did not realize until seeing that separation chart how much of a challenge is ahead for me and my $100 ebay centrifuge. Really excellent project/video as always!

[@MatthewStauffer]

What are you working on?

[@PedroDaGr8]

I hope your particles aren't too small. In the past when I was making 4-8nm diameter water soluble nanoparticles, I used to have to use an ultracentrifuge to pellet them.

[@evilcanofdrpepper]

well if it's balanced and built well enough you can always try to supe it up a bit lol.

[@Nighthawkinlight]

@@PedroDaGr8 I think I'll be ok. I'm looking for a range of particles from about 100-1000nm

[@unionmade1877]

You can get a refurbed air-driven ultracentrifuge for $100-200, which should be capable of 199,000 x g.

[@zilog1]

Fun fact, this triangular gran of the silver particles is why analog film companies call some of their stock, TRI-grain or Delta. Extar has a tri grain and illford Delta has this shape. it makes for a higher definition exposure.

[@subliminalvibes]

I wanted to say this too.

[@davidwillmore]

And Kodak T-MAX films were made by using only tablate triangular prisms oriented perpendicular to the film plane This gave them maximum sensitivity and minimum grain size. Wonder how they made those crystals!

[@OhHeyTrevorFlowers]

TIL

[@herpsderps9205]

Fascinating! Throughout the video I was thinking about applying these to a paper or polymer substrate ie film. And I thought, hmmm I bet industry has checked this out.... thanks for the factoid!!

[@alexbrown1050]

That was fun. Thanks.

[@tjhowse]

A potentially fun follow-up experiment: Rig up a jig that lets you both illuminate the liquid with a specific wavelength OR sample it with the spectrometer in situ. This way you can turn off the illumination long enough to sample the absorption spectrum at regular intervals. It would be cool to watch the peaks shifting on the absorption spectrum in time-lapse.

[@1fareast14]

The reference video did that over 26hr, but with multiple solution runs

[@johnqpublic2718]

I'm definitely saving this for later. In a few minutes the kids go to bed and roughly 45 minutes later I shall kick back in my recliner with this on the TV. Glorious Saturday Night Commence!

[@skuzlebut82]

Nerding out with an Applied Science video after the kids are in bed. That sounds like paradise to me, no sarcasm at all. I love these videos!

[@stephanieparker1250]

I saw the notification of the upload when I was making dinner.. trying to hurry up so I can go relax and watch! 🙌🙌🙌🙌

[@pistol0grip0pump]

Ben, this is super cool, every time I see an upload from you I know I'm going to not only learn something new and cool but then end up down a rabbit hole for the next few weeks, lol so thank you :)

[@Prophes0r]

It also comes with a convenient stick that we can use to measure our own lack of accomplishment along the way.

[@33zakb]

I feel this same way. If Ben puts out a video it's going to be fascinating regardless of the topic.

[@arcrad]

9999999999999999999999999999999999999

[@bfx8185]

We need Ben clones to have videos much often :D

[@TheHuesSciTech]

If the reactivity of the particles is "encouraged" by a given wavelength of light, it makes sense to me that they'd therefore react and grow *until* they're no longer (strongly) absorbing that wavelength. If that's the reason, that also explains why irradiating with a lower wavelength of light doesn't shrink the particles. TL;DR: if we assume the reaction occurring here is strictly crystal growth and that reaction is *enhanced* by light absorption, then we expect both effects that you seemed slightly surprised by (absorption wavelength != exposure wavelength; and the inability to reduce the absorption wavelength.)

[@turun_ambartanen]

I agree. But have you found any resources that show size dependent absorption properties of silver nanoprisms? I found a calculator for mie theory of spherical particles which supports this theory, but it would be nice to check for prisms.

[@timmccormack3930]

I also noticed that in the third graph, the 405 peak has red-shifted somewhat. I think that aligns with what you're saying. (I'm also curious about the new large peak that appeared in the IR range after the first graph.)

[@xponen]

this explain why when he use the 450nm LED, with intention to "revert it back to original colour" the red-shifting/peak-shifting actually do the opposite and is much stronger because more crystal from 400nm can grow bigger when provided with 450nm light.

[@DogeMultiverse]

This is the same hypothesis I had. Also, for the colour to shift back, it may be because the larger particles just fell out of solution while un touched smaller particles grew larger. It is just an illusion of shifting back, the particles don't actually become smaller.

[@Muonium1]

I wish I had a friend like Ben IRL to just unashamedly totally nerd out with over spectroscopy, electron microscopes, cryogenics, lasers, x-rays, and superconductors.... 😿

[@BRUXXUS]

RIGHT?! hahaha.

[@57ar7up]

LoL who needs friends when you could tell GPT or another language model to be wtf you want it to be

[@chaosfactor927]

Ben, one of the ways that nanoparticles are prepared for TEM is to place a droplet onto your substrate, wait for some time for the particles to settle/adhere to the substrate, blot the supernatent out with filter paper, and optionally wash by dropping wash solvent and blotting. There are a lot of surface modification tricks to try to get more particles to stick, such as plasma cleaning, UV-ozone, spin coating charged polymer solutions, etc. It might take a few iterations of sample loading (e.g. apply multiple droplets) to get enough visible sample. Definitely not easy and unfortunately not well described in literature (generally passed down via institutional knowledge in labs studying nanoparticles).

[@thrustin64]

TEM is definitely the way to look at nanoparticles. Time to build a TEM Ben!

[@TheExplosiveGuy]

Dang, I never knew how much I wanted a multispectrum monochromatic LED light, that is a super cool idea! I've got 9 different wavelengths of laser pointers which are also very cool for studying light absorbtion in different materials but now that I see this video I need the LED equivalent. It's amazing how much LED technology has evolved in just the last decade, being able to get this many monochromatic LEDs with such a high output power for the relatively low price they cost is incredible. I also think a flashlight version would be pretty great too, with a wheel inside that rolls through all the different wavelengths so only one is on at a time, that would be neat...

[@Erhannis]

A few years ago I bought a bunch of different wavelength LEDs to experiment with what things look like under different "equivalent" lighting conditions. Then I never actually wired them up. They had quite a variety of inconvenient forms, haha. Maybe I'll just make his. XD

[@whatelseison8970]

Yyyeah, but compared to your lasers even the most monochromatic LED's are still pretty broadband. It's still a cool idea though.

[@dizzious]

Man I only have six wavelengths of lasers, unless we're counting frequency doubling as two.

[@brainretardant]

Get a nice prism optical glass or diffraction grating

[@benjaminshropshire2900]

I wonder how hard it would be to get a dense enough series of LEDs so that by adding temperature control (IIRC peek wavelength shifts with temperature) you can get any peek you want?

[@craoun6116]

One sidenote concerning the stability of the NaBH4-solution: You could basify it in advance (to like pH 10-11), which would increase it's lifespan by orders of magnitude. Just seems like a possibility, since the final reaction mixture needs to be basic anyway. So a mixed stock solution of NaOH and NaBH4 could be used instead of two separate ones, since the required amount of NaOH is also known (2mL 50mM NaOH stock solution)

[@jeolman1]

I love your old JEOL JSM T-200. I worked for JEOL for about 10 years in the early 90's. I had several of that model in my service area, along with the later 300 series models. They are a great little scope when working properly. The 10nm resolution is only with Gold on carbon @ maximum KV very short working distance. The sample must be heated to ~ 100C before being transferred to the vacuum. Also must have very good chamber vacuum. low e-6 torr minimum. It is a pain, and I can remember the struggles when resolution had to be demonstrated.

[@peterwilson4636]

When I needed to image citrate-terminated gold nanoparticles in SEM, I used to deposit them onto poly-electrolyte multilayers. Surprisingly simple to set up. Simply prepare your imaging surface (the CD ROM in your case) by alternatively dipping it in solutions of polystyrene sulfonate (PSS; a negatively charged polyelectrolyte) washing with water, then dipping into poly diallyl dimethyl ammonium chloride (PDAC; positively charged), and washing in water again. Repeat the process 3-5 times to ensure a good coating of the poly electrolytes. Make sure you finish the treatment with PDAC so the surface will tend to be positively charged, so that the negatively charged nanoparticles will adhere to the surface. Simply leave this surface in the nanoparticle solution for an hour or two and you should have a even monolayer of individual particles to look at.

[@tymoteuszkazubski2755]

Two ideas for reversing transition: 1) Add precursor silver particles over time to encourage stealing atoms from plates. 2) Try going one wavelength step at a time, preferably try it with a smallest wavelength step you can get.

[@Basement-Science]

I was thinking that too. Maybe doing 2) in the first place would lead to a better conversion from the start as well. From the electron microscopy it seems there should be much room for improvement potentially.

[@Zappero]

I love this channel. Every video is well researched and really well presented. The downside is we get a video every 2 months. 100% quality over quantity.

[@among-us-99999]

>every 2 months i think it takes longer to produce these

[@nitehawk86]

10:08 I have been wanting to build one of these to test out astrophotgraphy light pollution filters. Mouser sells some very specific LED wavelengths, such as 656.28 for Hydrogen Alpha.

[@timhooper1557]

Something to filter out Musk's Starlink satellite's would be great... For everyone else, my pic's would still be terrible! lol

[@among-us-99999]

The satellites only reflect sunlight, not really something to filter out optically

[@timhooper1557]

@@among-us-99999 I'll just filter out the all the wavelengths from sunlight then!.. ;)

[@45CaliberCure]

@@timhooper1557 "Since the Dawn of Time, Man has yearned to block out the sun."

[@byronwatkins2565]

I think photoelectric effect is interacting with plasmon resonances. Short wavelength (high energy) light causes electrons to be ejected from the particle surfaces and then the solvent captures a silver ion to neutralize the particle. This continues until the particle gets small enough that its plasmon resonance frequency equals the light's frequency; at this point, the plasmon resonance shields the particle's surfaces from the light. Once the particle is too small, no longer wavelength light can reach it to cause dissolution. You could check this model by adding some fresh solution to see whether the color could be reddened in that case. Adding fresh silver ions will allow all particles to grow until the photoelectric effect arrests the growth. Plasmon resonances will have normal modes in triangular prisms. Probably, the underlying fcc structure of silver plays a part in the triangular shape.

[@Scrogan]

That could be potentially confirmed by looking at silver’s photoelectric work function to see if the redshift corresponds to that difference in energy. I think.

[@byronwatkins2565]

@@Scrogan Bulk properties don't usually apply to nanoparticles.

[@turun_ambartanen]

This would be an argument for shrinking the silver nanoprisms, but against growing them, right? "This continues until the particle gets small enough" would push particles to smaller sizes, but never to larger ones, which we clearly see in the initial illumination. Please correct me if I misunderstood your comment.

[@ZoonCrypticon]

*"Tunable Dipole Surface Plasmon Resonances of Silver Nanoparticles by Cladding Dielectric Layers"* -Xiaotong Liu, Dabing Li- Nature scientific Reports 2015, "[...] In this article, tunable dipole surface plasmon resonances of Ag nanoparticles (NPs) are realized by modification of the SiO2 dielectric layer thicknesses. SiO2 layers both beneath and over the Ag NPs affected the resonance wavelengths of local surface plasmons (LSPs). By adjusting the SiO2 thickness beneath the Ag NPs from 5 nm to 20 nm, the dipole surface plasmon resonances shifted from 470 nm to 410 nm. [...]"

[@byronwatkins2565]

Small particles interact significantly less with long-wavelength light and grow until the dissolved ions are depleted. Large particles emit photoelectrons and ions and dissolve making them interact less. Equilibrium occurs when the light's frequency equals the particles' plasmon frequency.

[@thrustin64]

Great video! I worked and made AgNP for my SERS research in grad school at UCSB. I made "bare" borate capped nanoparticles with just borohydride, but they were very tricky to get right and unstable once any contamination got into them. You can also use citrate directly as a reducing agent to make "nanoegg" ovaloids by heating a AgNO3 and citrate solution. These will provide stable citrate capped AgNP. Also, majority of absorbed light usually goes into creating plasmons (surface plasmon resonance). The electrons excited by this process can go on to participate in reactions, like reducing Ag ions in solution onto their surface. Might be an explanation on why the AgNP grow irreversibly with intense light.

[@kylejacobs1247]

If particles are catalyzed to grow when they absorb light, it makes sense that they keep growing until they are all too large to absorb the LED light. This would make the particle absorption peak longer wavelength than the LED illumination bandwidth.

[@petergoestohollywood382]

What always fascinates me the most is how people somehow managed to figure out this works in the first place. Thanks for sharing.

[@PedroDaGr8]

The red-shift is due to inherent energy losses in the system (basically non-reactive vibrational modes). If you use flourescent nanoparticle systems as a model, I think it can help make sense of the situation. Basically, not all of the energy you put into the system is available for the output, be it fluorescence or building the particle. This is why the shift is always in the red (aka lower energy) direction comparted to the exciting wavelength.

[@scatteredvideos1]

This is probably the largest factor but it's also possible the other components are effecting the wavelength (glass, water etc)

[@DrakkarCalethiel]

Insanely obscure topics demystified and demonstrated is why I love this channel so much!

[@MacksCurley]

Yes, every video shines a light in an undiscovered corner.

[@AliHSyed]

You are one smort cookie. Truly one of a kind among the KZbin STEM community. Thank you for the content

[@ExaltedDuck]

This is really cool. When I was in school we made something like this but with a rather more mundane size selection... it was CdSe nanocrystals (at the time we were still calling them microdots) and they were grown via Ostwald ripening... basically start with a mixture of Cd and Se mercaptan salts suspended in molten parafin, then set to a specific temperature for several hours and depending on the temperature, that would determine the size/color. I'm sure I've forgotten some critical details... it was almost 20 years ago. One thing I certainly won't forget though... the odor of bezenethiol (or thiolphenol for those who swing that way). It was like an unholy blend of smoke and anus.

[@T3sl4]

I remember seeing a poster with that in the chem lab at my school -- a student had done the series showing the rainbow spectrum of fluorescence. Don't remember any of the chemical details though... just the pretty vials on the poster :)

[@xxxm981]

Now there is an experiment you won´t see in any school anymore.

[@PedroDaGr8]

I've done hundreds (if not thousands) of CdSe nanoparticle reactions in the past. We could easily hit emissions at pretty much every 5nm from around 500nm-700nm with FWHM in the range of 15-25nm. Pretty much nobody uses Ostwald Ripening anymore due to its inherent issues (namely population broadening, surface defects, etc.). Xiaogang Peng had an excellent article from 2001 (J. Am. Chem. Soc. 2001, 123, 1, 183-184) which really changed the synthetic science in the field and others have built on that. The understanding about exciton confinement, non-radiative pathways, etc. have resulted in some amazing particle structures (CdSe Core/Intermediate Layer/ZnS Shell being the most common structure with various coating/encapsulation techniques).

[@beryllium1932]

Aww c'mon. You're blowing smoke up my 😂

[@bitlunislab]

Awesome Project! About the red shift: Did you consider if the refraction index of the medium might have an effect? Or even the shape of the cylindrical container?

[@puskajussi37]

It would seem the crystals prefer growing over shrinking, like at 14:15. So if the crystals can vary in size, this could give the process a bias towards larger than optimal crystals. Thinking of the reversibility, maybe it would work if you tried in small, few nm steps. The full cystals might be too far away from the wanted wavelength for it to have serious effect.

[@turun_ambartanen]

You are somewhat correct! The index of refraction directly influences the wavelength* and therefore directly influences how materials react to light. However, since we never look at the optical properties of the silver particles outside of solution this doesn't matter. The wavelength is shifted when illuminating, when measuring the extinction, and when looking at the colors of the samples. The shape will likely focus the light a bit, just like a lens would. This may make the growth faster, but will not change the mechanism. *It's the wavelength and not the frequency, because E=hv (Energy is planck constant times frequency) and the energy is conserved

[@firSound]

It seems awfully similar to what goes on while using fluorophores in fluorescent microscopy. All fluorophores emit light at a longer wavelength than the wavelength they absorb. Basically, instead of losing energy as a function of brightness, a fluorophore (in theory) could emit as bright of light as the one used to illuminate it, but energy is still conserved of course and the fluorophore emits as bright of a light but at lower frequency/longer wavelength. Since the wavelength of illumination is depositing the amount of energy required for the particles to assemble to a given prism size, and no system is lossless, the prisms will assemble to absorb wavelengths longer than the wavelength required to stimulate self-assembly. Perhaps like fluorophores, they conserve energy in a similar fashion - i.e. A solution of a given prism size may absorb as much light (in amplitude) as the brightness of the light used to create them but at a longer wavelength, thus still conserving energy.

[@PedroDaGr8]

​@@puskajussi37 "crystals prefer growing over shrinking" This is in general true of all reactions, it takes less energy to make a bond than to break a bond. At least the ones that have a favorable forward direction. Additionally, in the case of nanoparticles, there is no guarantee that the "breaking" path follows the same path as the "creation" path. Often for optically active materials, irreversible oxidation pathways are a problem as they provide an alternate terminal pathway the reaction can take.

[@RKroese]

I would think that it would be the room temperature which is basically ir light. Would shift it in the red spectrum.

[@herpsderps9205]

"I'd like to show you these silver nanoprisms" Truly a man of my own heart

[@nitehawk86]

2:15 I love the branding on that Sodium Citrate. "It's Just"

[@fjs1111]

Ben, you focus on the coolest of engineering + physics

[@Dukey8668]

Hey Ben, you should check out this paper: Bensley, Robert D. “Natural Color Photography in Colloidal Silver.”. As the name suggests, it involves creating color photographs out of colloidal silver using a standard black and white emulsion. Very interesting stuff.

[@johnkukla9522]

They fail to mention it in the article, but Bequerel, Herschel and others produced solar spectra in full color on metal plates coated with silver chloride. Some of the surviving examples are quite striking. Many color films (in the past, maybe currently) use a layer of colloidal silver between the blue-sensitive layer and the red / green sensitive layer beneath as a filter. Kodachrome, in particular, was well known for this

[@Dukey8668]

@@johnkukla9522 The color images produced by Becquerel and others using the early processes are fascinating, but I believe that it operated more on the principles of Lippmann plates than colloidal effects. And you are correct about the colloidal silver in color film, but it merely acted as a yellow filter to block blue light from reaching the red and green (or complements if negative) emulsion layers.

[@johnkukla9522]

@@Dukey8668 CNRS (the French National Centre for Scientific Research) did a study on these several years ago, and concluded that the colors were due to the presence of silver nanoparticles in the images. There's a press release available, but I have not found an accessible copy of the research paper. I'm not sure if Lippman - style interference phenomena would be possible with silver-chloride based materials that do not have (conventional) spectral sensitivity beyond the UV / Blue. As an aside, have you ever had the opportunity to see a Lippman photograph? I've never had the pleasure of seeing an original, but I've seen some modern work, and they are absolutely gorgeous beyond words. The emulsions are fairly straightforward to make, and this has been on my short list of projects to do for quite some time.

[@TechGorilla1987]

I have never clicked on a notification quicker than this one.

[@skuzlebut82]

I haven't either! Apparently I was the 1st comment, too. Let's me tell the people that just say, "First," that they're not.

[@PaulHigginbothamSr]

This guy made the very best video I have ever seen when he made a very low temperature beaker go below 100 degrees below zero in a two stage cooling beaker that makes the atmosphere separate into liquid components by repairing a unit that can even make dry ice.

[@Scrogan]

The brief look I made into gold nanoparticles suggested they were much simpler to make, I think they used citric acid as both a reducing agent and an anti-clumping agent.

[@nate_0723]

Neat! Sounds a lot like the chemistry of film photography!

[@imnotahippie22]

I love watching your content when chronic pain wakes me up in the middle of the night and it takes 2 hours for a nerve blocker to do it's thing. Keeps me very focused on what your doing and talking about so I don't feel as much pain. Thanks again. Your awesome! 😎

[@_spartan11796]

Always pumped to see you post. Hope you are doing well!

[@tjackman]

I always get excited when the electron microscope gets screen time! I think projects on this scale are some of the most interesting.

[@stevo450ify]

This is literally like my biology, physics and chemistry classes from school but for adults that I actually enjoy 👌

[@randyhavard6084]

It's great to see people so curious that they are willing to go through so much effort, basically just for fun.

[@JonasHortell]

Your videos are all great, your attempts to taker it further are always interesting.

[@AmirHakimiRezaei]

As always, thank you for a great video Ben!

[@DaneJessen101]

This man deserves respect. He is the Bob Vila of shop tech.

[@ericwilner1403]

That's science for ya... the answer to any question provokes several new questions that you otherwise never would have thought to ask. This also illustrates the difference between an experiment and a mere demonstration.

[@iteerrex8166]

Hey Ben always good to hear from you.

[@stephanieparker1250]

Great video! I love that you explain your process and any adjustments or changes you made along the way. 🙌

[@the_bootloader]

Great stuff Ben ! The optical properties of silver are fascinating. Photography, mirrors and now colorful nanoparticles.

[@captainboing]

Amazing detail and tenacity as usual. Fabulous to see really interesting chemistry in such complete "stories"

[@UwUSAH]

Every video you release blows my mind. Thank you so much and keep up the amazing research! ☺️

[@dave7038]

I'd love to see a multispectral photographic imaging project using that light. Put an ancient papyri document (or whatever document you have handy if you don't have any ancient papyri lying about) flat on a vacuum plate with a monochrome astrophotography camera above it with the light at low angle. Image the document at each wavelength. Rotate the light 15deg around the center of the document, image again, and repeat through a full rotation. Then rotate the angle of the light up 15deg and repeat the entire process again. Ideally the light should be collimated (maybe a bigish fresnel?), and maybe place some filters over the LEDs to narrow the frequency range. Write a bit of software to display one of the ~2100 images from the set based on three inputs that select the lighting angles and frequency. The idea is to reveal hidden details in the document.

[@christopherj3367]

so cool to watch thanks Ben, love watching your videos.

[@thomasw6169]

This guy is so smart, it always hurts me to watch while being interesting at the same time.

[@AaronJarecki]

Just, wow. Thank you so much. I'm going to be learning about silver nanoparticles for the next week

[@BigParadox]

I didn't really have time to watch this, but thought I will just watch some introductory part in the beginning. But I couldn't stop, watched the whole thing! Very interesting stuff!

[@-Graham]

Truly fascinating! Thankyou for your insight and your dedication to experimentation! Your content never ceases to amaze and inspire my mind.

[@CRneu]

I love these videos. You present knowledge in such an honest and valuable way. Major kudos! Lots of folks can learn a lot from these videos. I can only parody what others have said, which is that you present such advanced knowledge in such a simple way that it makes the knowledge digestible. It greatly appreciate it.

[@vincei4252]

Thank you so much. I snagged all the parts on Digikey to build the broad spectrum LED board. I was planning to use a selection of noble gases for same but this is so much easier! This will also be great for the calibration of my telescopes optical spectrophotometer without having to point at known stars. Awesome content as always.

[@papa_gowon]

You're an icon of DIY science!

[@-feonix48-47]

You’re a wizard, I absolutely love your work

[@kevgermany]

Love your videos. Really makes me think and wonder. Guess this goes back to the effects of light on silver that was exploited by film for so long. Thanks.

[@ManWithBeard1990]

There's a sweet irony about mentioning the hydrated forms of chemicals, and using the bag that says "It's just sodium citrate, nothing else!" on it as an example.

[@war_kittens]

Super funky. I've only seen this with gold nano particles, but that was a while ago. Love this.

[@gth042]

Science aside for a moment, your opening clip was framed into an incredibly inviting scene. Seriously, let a few weeks go by and just pause at 0:00 to admire the artistic thought that went into the shot.

[@SpicyDuckling322]

Great video! You always have such great content!

[@ElGatoLoco698]

I want one of those lights. Adjusting light color based on it's wavelength. it's so elegant. Genius. I couldn't build one if you gave me a year and unlimited budget.

[@mwethereld]

Another phenomenal video mate! I love all your content! Always engaging!

[@GeoffryGifari]

nice to have you back!

[@call_me_stan5887]

I gotta watch this when I have some more time - your channel is super interesting! :) I really respect the effort you put into making videos - they are outstanding!

[@kaharagin]

Thank you for the curious 🧐 work and sharing it with everyone. You are Awesome ManManaMan ✔️

[@sce-to-aux]

Super interesting! Always a pleasure to watch your videos…

[@TheBookDoctor]

Fascinating, as always!

[@illustriouschin]

I'm surprised such a low density of a few shattered snowflakes make such good structural pigments. Thanks for the great science again.

[@reavery2k]

this is wild. thanks a million for sharing and doing all of this

[@spiderjuice9874]

You never disappoint!

[@cylosgarage]

I recently discovered that CMDITR channel as well! Some really awesome technical content on there

[@ki4dbk]

Absolutely amazing. Thank you for sharing this!

[@patrickgassenbauer7070]

Really interesting video! It's also refreshing to hear which steps did not work in your process.

[@JO-ch3el]

As a layperson with no education in science I watch pretty much all of your videos until the end. You're very good at explaining things and I'm always amazed at the breadth of your skills and knowledge and the amount of work you put into your projects.

[@ChrisB257]

Super project Ben - great to see. :)

[@MrChaluliss]

Brilliant video. Really stimulating and enjoyable.

[@ZoonCrypticon]

@14:10 according to your assumption, one could make an artificial paper with enclose microdroplets of silver nanoprisms, which then could be "imprinted" by projecting a multicolored master image at 3 (or more, here just to stick alongside the RGB concept) specific wavelengths after each other, and so "save" a colored photo on type of "nanoparticle" paper.

[@meatsweatsland]

I don't know; this is my first video I've watched from this channel but when I heard that "...pretty crazy. Right?", something clicked in my mind.

[@prla5400]

Thanks, applied science after so many months!

[@MrGustavier]

Excellent, as always.

[@RobertSzasz]

Apparently bspp acts as a slow oxidizer in the original process. It breaks down over time making the photochemical reduction more and more preferable.

[@newtonbomb]

This is the kind of content that keeps me on youtube.

[@OakesProject]

Great content! Thanks for the work you put into this!

[@AtlasMTBRider]

Awesome video as always.

[@andymouse]

I've work with EM's and know the pain of sample prep !...cheers.

[@maxzet368]

Haven't seen the video yet, still gave a thumps up, because i know all his videos are great.

[@quackerzdb]

Amazing as always

[@RabeHK]

An ultra sonic bath also works great for degassing solvents especially if you use it in short bursts. Heating the solvent also is a cheap and easy way to do it. It is great to see what you do in your garage, while we often struggle with stuff in a multi million dollar lab.

[@scottwilliams895]

It's cool that you're investigating by using the tool you have, electron microscope. The particles seem like a *really* good opportunity for diffraction studies.

[@larrykent196]

As always well done and interesting. Thank you for sharing it. Cheers!

[@recklessroges]

Always interesting. Always well explained. Thank you.

[@JohannSwart_JWS]

The only channel where I hit the like button before even watching it. You may want to try raising the temperature (a little) during the reversal experiment. Temp has a huge influence on reaction kinetics, as you know.

[@stephanieparker1250]

I love how your electron microscope looks like it was developed at the Los Alamos Trinity Lab.

[@initialb123]

Amazing work !

[@Dyas777]

I love your videos so much!

[@turun_ambartanen]

Amazing video. I have a few comments and ideas: 1. You're talking about the *absorbance* of your sample at the end, but you are measuring the *extinction.* There is a big difference, because these particles *scatter* very strongly (as seen by the nice color range shown in the thumbnail), and what is transmitted is the source minus scattering and minus absorbance. 2. You could maybe filter the nanoparticles with a reverse osmosis filter. Just an idea, but you already got nice pictures anyway! 3. My theory for the growth mechanism is the following: If you irradiate a sample of silver nanoparticles they will absorb some of the light. However, this absorption may depend on the size of the nanoparticles. If small particles absorb more light than big ones they get fed energy and are more unstable, leading to dissolution and agglomeration into bigger particles. This would explain why you can't shrink particles by illumination - the big particles don't absorb as much energy and therefore have no reason to dissolve into smaller particles. This explanation does not offer a compelling reason for the spectroscopy results at 25:40, but I would argue that the spectrum just shows the emergence of smaller particles from remaining seed material, rather than the dissolution of the bigger prisms. The difference between the blue and black curve at 550nm is not that significant in my opinion (based on the shown sample size of 2, more spectra to compare would be nice) I have not yet found a simulator for silver nanoprism spectra, but there are online tools to calculate mie theory for spherical particles*. The extinction spectrum matches nicely to your measured data, -but the absorbance of the spherical particles does not fully support my explanation, as the difference by particles size (for spheres) is not very large- [EDIT: scrap that, the simulator I used uses a varying y axis. The absorbance is significantly size dependent]. This may very well be different for prisms though, any resources for calculating the spectra of silver nanoprisms are welcome! *KZbin likes to delete comments with links to further resources, so I'll not link directly here, but instead try in a comment below this one. I'm sure you'll find one by googling "Javascript Mie scattering calculator" or similar.

[@turun_ambartanen]

Attempting to link: saviot.cnrs.fr/mie/index.en.html You can set the material and the size of the nanosphere and it will show you a plot of the extinction, absorbance and scattering quality factor, which roughly corresponds to what the instrument in the video is measuring.

[@OG.Spirit]

Nice work! Thank you for experimenting, it keeps me entertained. Very interesting videos!

[@important9836]

Neat! Similar to the blue butterfly, the first time I learned of this visual phenomenon was when I found out the Bluejays I gave peanuts to at my window were actually brown!