I have just received a quote for a spectrophotometer I think we should acquire as soon as possible. At the last meeting it was agreed that we should acquire a spec, and I volunteered to teach a regular class on the operation and applications of this very useful tool. For those of you who are not familiar, let me go over the uses of spectrophotometry and why I think this particular instrument is a good fit for us. My apologies to those for whom the background is too basic.
A spectrophotometer in simplest laymans terms tells you exactly what colors something contains, and how much of each. A spectrum is a graphical representation of the exact intensity of each “color” in a beam of light. all the colors in a beam of light. “Colors” in this context means frequencies of light. If we generate an electric field that reverses direction 430 trillion times a second (from say, pushing a positive charge upward to pushing the same charge downward) we perceive that as the color red. If the field reverses only 300 trillion times a second, our eyes cannot perceive it at all, and this light is called “infrared”. If the field direction reverses 101 million times a second, it happens that you can decode that to obtain beautiful classical music, since a local station uses that frequency to transmit. We then call it radio waves instead of light, but this is arbitrary; it is just light of a different color. So are ultraviolet rays, x-rays, and gamma rays. The human eye sees an infinitesimal range of frequencies, from 430 to 770 terahertz, that we call visible light. Even that tiny fraction of the spectrum, we see in an extremely distorted and non-quantitative way. Yet we are all aware of how much information even our nearly colorblind eyes give us about the world. We can tell what things are made of, even the composition of complex mixtures, from the characteristic mix of colors in their spectra (plural of spectrum). Through the various marvelous instruments of spectrophotometry, we can observe the entire spectrum, with the color vision gods must have.
No, sadly no single instrument does that for us, and the specific instrument I recommend lets us see and measure wavelengths from 200 to 900 nm (frequencies from 516 terahertz to 1500 tearhertz). This range includes many of the signature wavelengths for compounds we want to analyze. We can also coax materials not normally conspicuous in this wavelength range to reveal their presence by generating or absorbing light in this range, by fluorescence or complexation or other tricks. It is also possible to rig a sample so that some property such as temperature, pressure or pH causes a change in color; it is then possible to follow changes in that property by feeding light from the sample through a fiber-optic probe to the spectrophotometer. (That depends on having a modular spec like this one).
Lest anyone be intimidated, spectrophotometer is way easier to use than most of the tools at the space and I can teach anyone at the space to identify and quantitate compounds in one lesson. Most of the art in spectrophotometry is knowing your sample, and what various colors mean. One simple exercise would be giving a class an unknown and having them identify it from its spectrum, or tell wheteher a sample is pure or contaminated.
Anticipated questions:
- Why is this thing so expensive? I saw a [insert cheap spec] on amazon for 30 dollors!
believe me, you get what you pay for.
a) If you only want to see the visible range (same as what you see with plain eyes, except quantitatively) you can save a lot of money, because to measure ultraviolet needs an ultraviolet lamp and other goodies which are pricey. I plead very strongly that the uv range is worth it, particularly for fluorescence.
b) This is a modular spectrophotometer that can be configured to work like several different instruments. It can work as a spectrofluorimeter, which is generally a second instrument as expensive as a spectrophotometer, so 2 instruments for price of one, almost. It can be adapted to measure emitted light (for measuring output of LEDs, for example) or reflected light off a surface as well as light transmitted through a sample. It is simple enough for elementary uses but ingenious makers will find ways to do quite advanced kinds of measurements with it.
I know there are makers ou there who have applicatios for a spec who do not participate in the science group. I invite those people now to participate in this thread and tell us what you could do with an ocean optics modular spectriophotometer when we have one at the space. Please check the link below to see its capabilities. This would be the usb-2000 model, but very similar to the current model described in the link:
here is a youtube video:
Here is the quote:
pectro Photon
part of a Grey Eagle Industries Inc. company
3208 East Colonial Drive, #112
orlando, FL 32803
United States
[email protected]
[email protected]
INVOICE
Invoice #:
30398
Invoice date:
Aug 16, 2017
Due date:
Aug 16, 2017
Amount due:
$1,219.97
Bill To:
[email protected]
Description
Quantity Price Amount
Ocean Optics USB2000 UV-VIS 200nm to 825nm, 25um slit, #2 grating
1 $799.99 $799.99
generic cuvette holder with 4 input/output ports. Includes 2 free beam SMA-905 connectors
1 $60.00 $60.00
Generic brand 200um 24" long fiber cables. good from 200nm to 1100nm
2 $39.99 $79.98
Ocean Optics Spectrasuite software sent electronically. 32 or 64 bit
1 $0.00 $0.00
Ocean Optics Tungstum Deuterium light source w/ AC adapter
This light source is the guts only. No external case included.
1 $260.00 $260.00
Subtotal $1,199.97
Shipping $20.00
Total $1,219.97 USD
Terms and Conditions
30 day money back warranty followed by a 90 repair warranty. Thank you for your business.
Chris
