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First RMS Numbers on the Olis DB 620
May 29, 2003 - No processing of the data was done to achieve the following RMS noise levels. The data are literally “raw”: no averaging, no filtering, no smoothing. In each case, 1000 points were collected in the allotted time and these were fitted to a straight line with the root mean square (RMS) calculated.
Collection Time
(seconds) |
Wavelength
(nm) |
RMS Noise
(AU) |
| 0.001 |
250 |
0.0014 |
| 0.001 |
350 |
0.00037 |
| 0.001 |
450 |
0.00030 |
| 0.001 |
550 |
0.00036 |
| 0.01 |
250 |
0.00079 |
| 0.01 |
350 |
0.00022 |
| 0.01 |
450 |
0.00016 |
| 0.01 |
550 |
0.00018 |
| 0.1 |
250 |
0.00028 |
| 0.1 |
550 |
0.00007 |
| 0.5 |
250 |
0.00017 |
| 0.5 |
550 |
0.00005 |
| 1.0 |
250 |
0.00016 |
| 1.0 |
550 |
0.00005 |
Even lower noise accompanies use of a 150 watt xenon arc rather than the default choice 75 watt xenon arc! The brighter lamp adds a little more than $1K to the price and is standard in absorbance & CD systems to be used below 180 nm.
The Olis DB620 is our small scanning absorbance spectrophotometer, optimized for kinetics (e.g., stopped-flow) and so stable and noise-free that it is ideal for lengthy thermal melts and equilibrium studies, too.
The standard model uses a double grating scanning monochromator, two photomultiplier tubes and true dual beam detection, 2 nm bandpass, and a 75 watt xenon arc steady-state lamp; a Pentium computer with the Olis 14 bit 2 MHz A/D and the Olis Electronics Module are used for controlling the timing and data acquisition. The Olis SpectralWorks DB620 software is used for setting up the experiment, collecting and viewing the 2D and 3D data, fitting the 2D and 3D data, and storing the results as binary, ASCII, and Excel files.
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