Infrared radiation imaging with

Synchrotron Radiation as a Source for Infrared Microspectroscopic Imaging with 2D Multi-Element Detection... 

The infrared radiation caused by the heat of reaction of an enantioselective enzyme-catalyzed transformation can be detected by modern photovoltaic infrared (IT)-thermographic cameras equipped with focal-plane array detectors. Specifically, in the lipase-catalyzed enantioselective acylation of racemic 1-phenylethanol (20), the (K)- and (S)-substrates were allowed to react separately in the wells of microtiter plates, the (7 )-alcohol showing hot spots in the IR-thermographic images (113,114). Thus, enantioselective enzymes can be identified in kinetic resolution. However, quantification has not been achieved thus far by this method, which means that only those mutants can be identified which have E values larger than 100 (113-115). 

The question was whether we could effectively shift the absorption spectrum of HABI by synthetic means or by addition of sensitizing dyes. Both approaches showed promise. Ultimately, we found the synthetic approach was more effective but many years later, when we sought to form images with near-infrared radiation, we had to depend on sensitizing dyes to shift the absorption. 

Fig. 28 Illustration of the principle of selective imaging by use of specific spectral bands of Raman scattered radiation. (Reproduced with permission from G. J. Rosasco, Raman Microscope Spectroscopy, in Advances in infrared and Raman Spectroscopy, Vol. 7. Copyright 1980, Heyden Son Ltd.)...

Phosphors. Infrared radiation can stimulate the emission of visible radiation from certain types of phosphors which have been previously excited by ultraviolet radiation. Becker and Risgin [2.71] have reported that self-activated ZnS crystals have exhibited both visible luminescence and photoconductivity when stimulated by radiation in the 1-3 pm interval. Geusic et al. [2.72] have shown that rare earth phosphors can convert very near infrared (0.93 pm) radiation into the visible with an efficiency as high as 1 %. Although phosphors can be employed to convert images directly, their lack of sensitivity has limited their usefulness. 

The widespread application of 10.6 pm heterodyne detection for communications, radar and infrared active imaging is presently restricted by the need to cool the detectors below temperatures obtainable from thermal electric coolers ( 180 K). Presently the main reason for cooling 10.6 pm heterodyne detectors is to reduce the thermal generation-recombination rate in the photoconductor or the diffusion current in diodes to a level that can be overridden by available laser local oscillator power. In general the use of photoconductors (with band gaps tailored for 10.6 pm radiation) seems to be a realistic approach to operation at 180 K or above. Since the thermal generation-recombination rate is of the order of 10 /t hole-electron pair per cm at 180 K it follows that a 1 pm thick, 10 cm area photoconductor with a carrier lifetime (t) of 10" s would require 1 milliwatt of LO power to approach hvB detector sensitivity at bandwidths of... 

Formulations similar to those used in Dry Silver but without the AgX component are light stable but can be imaged thermally. The silver behenate develops to form a black silver image where (and only where) heat is applied. Materials of this type were originally intended for reflex exposure. Here the film is sandwiched with a document and exposed to a source of infrared radiation. The ink on the document absorbs the infrared and converts it to heat, which initiates development of the film, where it is in contact with the ink image on the paper. Overhead projector transparencies, sometimes called view graphs, ... 

Several other ionization methods and MS technologies have been investigated for possible use for imaging. Atmospheric pressure infrared MALDI (AP IR-MALDI) and mid-infrared laser ablation with electrospray ionization (LAESI) have been reported and use focused laser radiation for ambient sampling with no sample preparation or chemical modification required. In these... 

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