Ultraviolet Absorption Spectra at Reduced Temperatures. I. Principles and Methods

摘要

Low temperature absorption and fluorescence spectra of solids, liquids,udand solutions often reveal increased spectral detail of use in analyticaludprocedures and molecular structure studies. Nevertheless, while qualitativeudobservations of the influence of liquid air temperatures upon opticaludproperties were undertaken very early, investigations of theudabsorption and fluorescence of organic compounds at the temperatureudof liquid nitrogen (-195.6°; 77.4 °K.) and below have appeared onlyudsporadically. Because of the potential usefulness of the technique we have undertaken a systematic study of the low temperature spectraudof substances of biochemical interest. The present paper discusses theudmethods employed; subsequent papers will deal with the experimentaludresults. In this work, we have emphasized the wave-length location ofudabsorption bands and the accurate determination of relative optical densitiesudrather than precision in the determination of absolute optical densities,udthus permitting the use of simpler methods than would otherwise beudnecessary.