Transient infrared emission spectroscopy

Abstract

BetIOn. J.-M.; Desmadrll, M.; Mitraki, A.; Yon, J. M. Biochemkby 1984, 23 6654-6681. Craig, S.; Hollecker, M.; Creighton, T. E.; Pain, R. H. J. Mol. Biol. 1985. 185. 681-687. Brems, D. N.; Plaisted, S. M.; Havel, H. A.; Kauffman, E. W.; Stodola, J. D.; Eaton, L. C.; White, R. D. Blochemisby 1985, 24, 7662-7668. Holzman. T. F.; Brems, D. N.; Douaherty. J. J.. Jr. Biochemlst~y 1986, -. 25, 6907-6917. Kuwaiima, K.; Hiraoka, Y.; Ikegushi, M.; Sugai, S. Biochemistry 1985, 24 ~ 074-88 1. Frontlcelli, C.; Bucci, E. Biophys. Chem. 1985, 23, 125-128. Brems, D. N.; Plaisted, S. M.; Dougherty. J. J., Jr.; Holzman. T. F. J. Horwltz, J.; Strkkland, E. H.; Billups, C. J. Am. Chem. SOC. 1970, 24 1 , 449-457. 585-590. 91, 184-190. 3205-32 13. 92, 2119-2129. Havei. H. A.; Kauffman, E. W.; Plaisted, S. M.; Brems, D. N. Biochemistry 1986, 25, 6533-6538. (61) Wlllis, P. R.; Georgalis, Y. Translent infrared emisslon spectroscopy (TIRES) is a newmethod that produces analytically useful emlsslon spectra from optlcally Ihlck, solid samples by greatly reducing selfabsorptlon of emitted radlatlon. The method reduces selfabsorption by creating a thln, short-llved, heated layer at the sample surface and coHectlng the transient emission from thls layer. The techdque requires no sample preparation and may be appiled to both moving and statlonary samples. The slngle-ended, noncontact TIRES measurement geometry is Ideal for on-llne and other remote-senslng applications. TIRES spectra acquired via a Fourler transform infrared spectrometer on movlng samples of coal, plastic, and palnt are presented and compared to photoacoustlc absorptlon spectra of these materlals. The TIRES and photoacoustk results are In close agreement as predlcted by Klrchhoff's law.

Spectral Depth Profiling of Arbitrary Surfaces by Thermal Emission Decay—Fourier Transform Infrared Spectroscopy

“…17 However, the low sensitivity of the diffraction grating instrument and the low spectral resolution (Dl/l ø 0.1) of the interference lters limits their range of applications. Jones and M cClelland rst exploited the multiplex advantage of an FT-IR interferometer to measure high-resolution transient thermal emission and transmission spectra using a variety of excitation sources (pulsed and sinusoidally modulated lasers, 18,19 hot and cold air jets 20,21 (a) semi-in nite homogeneous sample, (b) two-layer samp le with optically thin top layer, and (c) two-layer sample with optically thick top layer.…”

Transient infrared emission spectroscopy by pulsed laser excitation

“…When a material is heated to a uniform elevated temperature, all parts of it both emit and reabsorb infrared radiation, and this self-absorption of previously emitted light severely truncates and alters features in the emission spectra of optically thick samples. The resulting emission spectra closely resemble blackbody spectra and contain very little structure characteristic of sample composition (1) infrared emission spectroscopy (TIRES) that produces analytically useful emission spectra from optically thick samples was introduced (2). In TIRES a laser is used to rapidly heat a thin surface layer of the sample and emission from this layer is gathered before it thickens and cools by thermal diffusion.…”

“…This effectively minimizes self-absorption by limiting the emitting and reabsorbing to an optically thin volume. In the previous paper on TIRES (2) the background and characteristics of performing TIRES using both continuous-wave (CW) lasers with moving samples and pulsed lasers with both moving and stationary samples were discussed, but only results obtained by using a CW laser were presented and discussed.…”

“…Such a small Zmax can be difficult to produce by CW-laser TIRES. If D were the same and r were 0.4 cm, as it was for the earlier CW-laser TIRES work (2), a sample velocity of 40 m/s would be needed to attain a 9-µ Zmax. The small values of Z^t hat are readily achieved with pulsed-laser TIRES result in spectra suffering from only minimal self-absorption.…”

“…Such low-Zm" spectra have a larger fraction of the total emission in the structured portion of the emission (at the expense of the blackbody-like portion) and have better spectral contrast (that is, less apparent saturation) in the resulting emittance spectra. very similar to those used for CW-laser TIRES (2), but the electronic arrangement and signal treatment were modified in a manner similar to that used by Leone and co-workers (3,4) to study chemical kinetics by infrared emission. A disk either made of or covered with the sample material was mounted on the shaft of a variable-speed motor and placed at the normal source position of a Perkin-Elmer 1800 Fourier transform spectrophotometer.…”