Infrared absorbing

A commonly used detector is a Golay cell, in which there is a far-infrared absorbing material, such as aluminium deposited on collodion, inside the entrance window of the cell. 

Ai- 4-(bis[4-(phenylamino)phenyl]methylene)-2,5-cyclohexadien-l-ykdene -3-methyl-ben2eneaminesulfate [57877-94-8] (20) have been claimed as positive CCAs (65). The absorption spectra of the triaryknethane dyes can be extended into the near-infrared region. The use of triaryknethane dyes as infrared absorbers for optical information recording media (66) and as infrared color formers in carbonless copy paper has been claimed. 

The cyanine class of dyes is also useful in biological, medical, laser, and electro-optic appHcations. Dyes marketed as Povan [3546-41-6] (5) and Dithiazanine [7187-55-5] (6) are useful anthelmintics, and Indocyanine Green [3599-32-4] (7) is an infrared-absorbing tracer for blood-dilution medical diagnoses. "Stains-AU." is a weU-studied biological stain (8) and Merocyanine 540 s photochemotherapeutic activity is known in some detail (9). Many commercially available red and infrared laser dyes are cyanines (10). 

Table 12. Examples of Near-Infrared Absorbing Dyes...

M. Matsuoka, ed.. Infrared Absorbing Dyes, Plenum Press, New York, 1990. 

The primary reference method used for measuring carbon monoxide in the United States is based on nondispersive infrared (NDIR) photometry (1, 2). The principle involved is the preferential absorption of infrared radiation by carbon monoxide. Figure 14-1 is a schematic representation of an NDIR analyzer. The analyzer has a hot filament source of infrared radiation, a chopper, a sample cell, reference cell, and a detector. The reference cell is filled with a non-infrared-absorbing gas, and the sample cell is continuously flushed with ambient air containing an unknown amount of CO. The detector cell is divided into two compartments by a flexible membrane, with each compartment filled with CO. Movement of the membrane causes a change in electrical capacitance in a control circuit whose signal is processed and fed to a recorder. 

Reilly, M. S. Arasteh, D. and Rubin, M. ( 1990). The Effects of Infrared Absorbing Gasses on Window Heat... 

Fig. 6-2 Comparison of infrared absorbance of a vertical column of atmospheric CO2 and H2O vapor. The nearly total absorbance by H2O between 5 and 7 /

Recent work in our laboratory has shown that Fourier Transform Infrared Reflection Absorption Spectroscopy (FT-IRRAS) can be used routinely to measure vibrational spectra of a monolayer on a low area metal surface. To achieve sensitivity and resolution, a pseudo-double beam, polarization modulation technique was integrated into the FT-IR experiment. We have shown applicability of FT-IRRAS to spectral measurements of surface adsorbates in the presence of a surrounding infrared absorbing gas or liquid as well as measurements in the UHV. We now show progress toward situ measurement of thermal and hydration induced conformational changes of adsorbate structure. The design of the cell and some preliminary measurements will be discussed. 

The infrared absorbance spectra were recorded at room temperature on a Fourier transform spectrophotometer (Biucker I.F.S. 110) with a resolution of 4 cm To compare the integrated adsorbances of the various samples the weight of the pellet and the Pd content were considered. The samples were placed in a heatable cell where the catalysts were treated "in situ". Different kinds of experiments were carried out ... 

Photo-thermal tumor ablation in mice using near infrared-absorbing nanoparticles. Cancer Letters, 209, 171-176. 

Reaction of pyromellitic anhydride with 1,1-bisdimethylaminophenyl-ethylene has been shown110 to yield a mixture of the bisphthalides 31 and 32 which are infrared-absorbing color formers on clay. 

The reaction of keto acids (79) having no amino group with 3-alkoxy-diphenylamines (80) is used to synthesize 3 -anilinofluorans (81), especially near-infrared-absorbing fluoran compounds (Eq. 6). 

Table 7 shows melting points of a few near-infrared-absorbing fluoran compounds (81) thus prepared. 

The first chapter of the book deals with leuco-spiropyrans and related spiro compounds, which constitute one of the classes of leuco compounds not of the redox type. Such materials are photochromic, and are of major technical importance. The author, Hiroyuki Nakazumi of the Department of Applied Chemistry at the University of Osaka Prefecture, is well known for his researches in functional dye chemistry, particularly photochromic materials, and he provides a very useful update of the field, covering mechanisms, synthesis, spectra and applications, together with a useful section on approaches to near-infrared absorbing photochromic dyes. 

Figure 10.9 Principles of optical data storage using near-infrared absorbers...

The bleaching of carotenoids was simultaneous with the formation of near-infrared absorbing intermediates in the microsecond timescale. The formation of an adduct ion-pair is instantaneous during the laser pulse (<10ns) with maximum absorption in the region 830-950 nm, depending on... 

Skibsted and coworkers (Mortensen and Skibsted 1996) have shown that upon the laser flash photolysis of carotenoids in chloroform bleaching of the ground state absorption is observed and there is formation of two near infrared-absorbing species ()tmax 920 and lOOOnm for 0-CAR). The species absorbing at about lOOOnm is 0-CAR + and, as with the carotenoid/CCl302 system noted earlier, the 0-CAR,+ is formed from the other species. The nature of the other species is not defined although an adduct or a neutral carotenoid radical is proposed. 

Many practical applications of cure characterization involve samples for which the data required to convert isocyanate absorbance to concentration is unavailable. The emphasis is often placed on rapid analysis of many samples rather than an exhaustive characterization of a single sample. It is particularly desirable to develop a procedure which can determine the rate constants describing the cure reaction without converting the infrared absorbance curve to concentration. This has been accomplished by normalizing the data in such a way that the rate constants are determined from the shape of the cure curve. 

Twenty scans wepe co-added to produce one spectrum at a resolution of 4 cm every 30 seconds. The reaction was followed by monitoring the absorbance of isocyanate as a function of time. Film thickness changes were compensated for by normalizing the isocyanate absorbance to the 1446 cm band which remains constant in absorbance during the reaction. The infrared absorbance of the free isocyanate is converted to concentration by comparison to the absorbance observed in a similar sample which has no functional groups with which the isocyanate can react. 

Shankar, S.S., Rai, A., Ahmad, A. and Sastry, M. (2005) Controlling the optical properties of lemongrass extract synthesized gold nanotriangles and potential application in infrared-absorbing optical coatings. Chemistry of Materials, 17, 566-572. 

Kim SH, Kim JH, Cui JZ, Gal YS, Jin SH, Koh K (2002) Absorption spectra, aggregation and photofading behaviour of near-infrared absorbing squarylium dyes containing perimidine moiety. Dyes Pigm 55 1-7... 

Fabian J, Nakazumi H, Matsuoka M (1992) Near-infrared absorbing dyes. Chem Rev 92 1197-1226... 

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