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

Low temperature absorption and fluorescence spectra of solids, liquids, and solutions often reveal increased spectral detail of use in analytical procedures and molecular structure studies. Nevertheless, while qualitative observations of the influence of liquid air temperatures upon optical properties were undertaken very early, investigations of the absorption and fluorescence of organic compounds at the temperature of liquid nitrogen (-195.6°; 77.4 °K.) and below have appeared only sporadically. Because of the potential usefulness of the technique we have undertaken a systematic study of the low temperature spectra of substances of biochemical interest. The present paper discusses the methods employed; subsequent papers will deal with the experimental results. In this work, we have emphasized the wave-length location of absorption bands and the accurate determination of relative optical densities rather than precision in the determination of absolute optical densities, thus permitting the use of simpler methods than would otherwise be necessary

Christiansen Filters for the Ultra-Violet

Gaydon and Minkoff have described a Christiansen filter designed to isolate the 2537 A. resonance line of mercury. We have been working for some time upon the general problem of the design of Christiansen filters for the isolation of various spark and discharge tube lines to be used in ultra-violet microscopy. We have amplified the work of Kohn and von Fragstein, and developed a series of filters employing benzene—alcohol mixtures with fused quartz chips, which can span the region 3000–4000 A

Use of Thin Films of Sublimate for Absorption Spectroscopy

We have previously described a method for the preparation by sublimation of thin films of polar materials for use in low-temperature spectroscopy. Similar films have been used by Brown and Randall for the same purpose, and by Blout and Fields for infra-red absorption spectra. Our continued study of the spectra of such films has revealed certain anomalies which should be given proper consideration in their analysis