How to measure size of gold or silver nanoparticles using UV Vis Spectrum

There is the relationship between the optical absorption spectrum of gold or silver nanoparticles caused by surface plasmon absorption (in particular, the plasmon resonance and its brodening ) and their sizes. The surface plasmon resonance is the coherent excitation of all the `free ’ electrons within the conduction band. The resonance does not give rise to the most intense absorption for very small clusters. For the larger particles (several tens of nanometres) the excitation of the surface resonance absorption can occurs in visible light region ( 400 -600 nm for Ag and Au nanoparticles). Such absorption spectra can be analysed using Mie theory. In particular, according this theory for nanoparticles smaller than the mean free path of the conduction electrons there is the relationship between the resonance broadening (γ) and the sizes of nanoparticles γ (r ) = γo + AυF/r , where r is the size of nanoparticle, A=3/4 for silver, γo is the velocity of bulk scattering (5•10 to 12 degrees s(-1)), υF is the Fermi velocity (for silver 1.39 • 10 to 6 degrees m/s). Using the experimental absorption spectra and this relation we can determine the size of nanoparticle.

Instrument: Double Beam UV Visible Spectrophotometer UV1901S

Features

1. Holographic Blazed Grating 1200 lines/mm, which ensures the low stray light.

2. Automated control system, which ensures the high stability and low noise.

3. Detachable sample room, which makes it easy to change accessories.

4. Spacious open-type light source room, which makes it easy to replace lamps.

5. Real double beam optical system.

6. 320*240 Graphic LCD Screen.

Powerful Functions 

1. Photometric Measurement: it can measure the Transmittance and Absorbance at different wavelengths simultaneously (Max 6 wavelengths)

2. Spectrum Measurement: Scanning on the Transmittance, Absorbance and Energy in wavelength range, and can do kinds of data processing, such as peak & valley detection, derivative calculation and spectrum operation.

3. Quantitative Measurement: Single wavelength, Double wavelengths, Three wavelengths and Multi-wavelengths measurement.

4. Kinetics Measurement: Time scanning and kinds of values calculation on the transmittance and absorbance at any set wavelength.

Technique Parameters

1. Wavelength Range: 190-1100nm.

2. Spectral Bandwidth: 0.5nm/1nm/2nm/3nm/5nm.

3. Wavelength Accuracy: +/-0.1nm (D2 656.1nm); +/-0.3nm full range.

4. Work Mode: T; A; C; E.

Copyright@YK Scientific Instrument Co.,Ltd

UV756CRT Split Beam UV Visible Spectrophotometer with Professional Software

UV756CRT is a high stability robust split beam spectrophotometer with a fixed 2nm spectral bandwidth.

The UV756CRT has a wavelength range of 190-1100nm. The instrument has automatically scanning function on full wavelength range with the Professional Software, which is supplied with the model as standard. The UV756CRT delivers the functionality and accuracy of an advanced instrument at affordable price.

Features & Functions

1. High performance fixed 2nm spectral bandwidth.
2. Low stray light 0.05%T.
3. Wavelength accuracy: +/-0.5nm
4. Improved optical system, 1200 lines/mm grating.
5. LCD Screen(128*64 dot matrix), which can display the standard curve and measured data.
6. Bulit in Ram, which can store 50 groups data and 10 standard curves.
7. Special wavelength control system, which ensures the high precision of wavelength.
8. Imported Tungsten Lamp & Deuterium Lamp, long service life(2000 hours).
9. Microcomputer data processing system, which ensures the stability.

Specifications:

1. Wavelength range: 190-1100nm
2. Wavelength accuracy: +/-0.5nm
3. Wavelength reproducibility: 0.2nm
4. Spectral bandwidth: 2nm
5. Transmittance accuracy: +/-0.05%T
6. Transmittance reproducibility: 0.2%T
7. Transmittance range: 0-200%T
8. Absorbance range: -0.30-3A
9. Concentration range: 0-1999
10. Stray light: 0.05%T@220nm, 360nm
11. Stability: +/-0.001A/Hour @500nm
12. Light source: Tungsten Halogen and Deuterium Lamps
13. PC Interface: USB
14. Printer Interface: Parallel
15. Standard functionality: Photometric Measurement (Quantitative, Multi-wavelength, Spectrum and Kinetic measurements with program cards based on Windows system)
16. Net weight: 12kg
17. Dimension: 52*45*32cm

Each unit is supplied with the following as standard:

• 1 x certificate conformity
• 1 pare of Quartz cells and 2 pares of Glass cells
• 1 program card
• 1 power cord
• 1 instruction manual
• 1 packing list

V721 Simple Single Beam Visible Spectrophotometer

This model is a simple single beam spectrometer. The wavelength is set manually from the dial on the front panel. Direct readout of transmission or absorption on the LED display. Measured values can be transferred to PC via the RS232 for further analysis. Low price and simple design make this model make this ideal tool for education or routine analysis. 

Technique Parameters:

1. C-T Monochromator, grating 1200 lines/mm

2. Wavelength range: 350-1020nm

3. Bandwidth: 6nm

4. Wavelength Accuracy: +/-2nm

5. Wavelength Repeatability: 1nm

6. Photometric accuracy: +/-1%T

7. Work Mode: T; A; C

UV Vis Spectrophotometer Scanning Screen Shot

UV1810S with Variable Bandwidth(0.5nm/1nm/2nm/4nm/5nm)

A customer, named Dr. Khaled, sent me picture above and asked me urgently: "the spectrometer suddenly give us the signal, can you help us fix it? "

According to my experience, the reason is that Tungsten Lamp was broken. So I told him why the spectrometer gave that signal. 

And after checking the date he bought the item, found that the model still in our guarantee. So I added: "Dr. Khaled, donot worry, the model is still in our warranty, we will send out the replacement Tungsten Lamp immediately."

Copyright@YK Scientific Instrument Co.,Ltd

I know you are not that kind of person!

It was in year of 2008, as it passed for several years, I could not remember the exact date of getting the inquiry from K, but his requirements are still clearly in my mind. It was not an exact inquiry, to be accurate, as he paid more attention on the company rather on the products. Due to the inquiry with detailed signature, I filed it to B. I think he is new or prepare into relative market.

After several times following, not any feedback. 

One day in Nov, I sent one email, which subject with his name, to check whether have requirements on the products he interested before. Unexpectedly, I got reply from K in few minutes, only several words: when did I send you inquiry? Do you have the original email?

I searched his first email and get back to him immediately. And he added me to his MSN.

My guess was right, he was new, one of his customer asked him to find supplier in China. As didnot know much of our products, I have to spare almost half day to talk with him on MSN. Finally, we won the order from his customer at the beginning of December. 

As per the contract, the delivery time was 25 days, which is just on Xmas, he didnot come for inspection. 

But soon, he won another order, which delivery time in Jan 2009. He said he would come for inspection and know more about us. There was a story for picking him up from airport.

He arrived Shenzhen airport firstly, and had to transit to Tianjin(I worked in Tianjin Then). While, the weather was not good and just had heavy snow, all the lines to Tianjin were hold.

So he had to go to Beijing, and he sent me a message to check whether it is possible to pick him up from Beijing Airport. Considering he did not know any chinese, we drove to Beijing. On the way back Tianjin, he pull out one CD from his trolley case. It was Indian songs. He said it could avoid boring. 

While, the journey would not be boring with him.

Though I left that company later, we still kept in touch with each other.

Yesterday, we talked on the phone, and I asked him, did you have that moment of suspecting me for cheating from the beginning? His tone was getting seriously, not even a minute, Sunny, I know you are not that kind of person. 

Thanks, K. It is the warmest comment I've heard!