Typical Modernization Procedures

After removing the strip chart recorder, the hundreds of pounds of circa 1960s circuitry, the multi-pot unit, and all other original control/recording hardware, we add:

1. A stepping motor under the monochromator, coupled to the wavelength drive input shaft with a zero-backlash chain. The new motor and monochromator drive ratio result in wavelength steps to half an angstrom (0.05 nm) and a maximum scan rate of approximately 20 nm/ second.
2. Olis mounts a second 200 step/revolution stepping motor to the slit width mechanism; it is with this motor that the Olis computer system controls system gain, and adjusts spectral resolution. The original, noisy mechanical slit stopping mechanism is replaced with a new, quiet one.
3. Olis positions an optical detector at the chopper wheel to provide a signal to the computer which is synchronous with the switching of the measuring light between sample and reference cuvettes.
4. We replace the original PMT with a new one with superior noise, dark current, and high gain performance. This new PMT has extended UV and extended NIR response, too. The original high voltage power supply is replaced with a programmable high voltage photomultiplier socket assembly.
5. We mount a precision FET input electrometer operational amplifier in the photomultiplier chamber to act as a photocurrent to voltage converter. The amplifier produces one volt output per ten nanoamperes of photocurrent.
6. We replace the original UV/Vis lamps with new air-cooled deuterium and tungsten lamps and modern regulated power supplies. Optionally, we can replace or augment these stable lamps with a high intensity light source (e.g., xenon arc lamp) for maximum illumination power (as when fluorescence or circular dichroism work will be done with the Cary monochromator).
7. An external Olis box, which interfaces between the monochromator and the recording computer, houses the rest: lamp power supplies, motor drives, calibration circuitry, and Windows communication hardware (including two 16 bit A/D/A converter chips).
8. The stripped and simplified instrument is fitted with a new front panel and top.
9. Multi-position cell holders, photolyzing flash photolysis accessories, stopped-flow mixing units, magnetic stirring blocks, automatic titrators, Peltier cells, high pressure cells, and other 'sample holders' can be added by Olis or the laboratory personnel.