Tatiana N. Brusentsova

Far infrared spectroscopy of carbonate minerals

Abstract This study presents far infrared spectra in the range 650-70 cm-1 of 18 common and rare carbonate minerals. Mineral samples of known provenance are selected and physically characterized to determine the purity of the crystalline phase and their composition. The fine ground mineral powders are embedded in polyethylene pellets, and their transmittance spectra are collected with a Fourier spectrometer. The far infrared spectra of different carbonate minerals from the same structural group have well-defined similarities. Observed shifts generally manifest the mass effect of the constituent metal cations. Remarkable spectral differences occur for different carbonates in the far IR region and may serve as fingerprints for mineral identification and are more useful identifiers of carbonate species than those in any other infrared range. For some of the minerals studied here, like kutnohorite, artinite, gaylussite, and trona, no far infrared spectra to that extend (up to 70 cm-1) have been found in literature.

Terahertz spectroscopy of TNT for explosive detection

Transmittance spectra of solid and vapor samples of trinitrotoluene (TNT) in the spectral range 0.6 to 10 THz at resolutions up to 1 GHz are reported. Uniform solid samples of ~100 &mgr;m thickness gave stronger absorption and more resolved structure than previous studies. New absorption lines for TNT solid below 100 cm-1 are reported. A heated 10 m multpass White cell was used for spectroscopy of the vapor. Strong absorption bands yield unexpectedly large absorption cross sections for the anticipated saturated vapor pressure at the cell temperature, leaving their assignment to TNT in doubt. These results indicate that path lengths exceeding 10 m and temperatures higher than 40 C, or significantly higher instrumental sensitivity, are needed for sensing of TNT vapor in the spectral range 0.6 to 10 THz.

Terahertz Spectroscopy of Acetone Vapor

Original terahertz spectra of acetone vapor-phase vibrational, torsional, and rotational transitions determine peak absorption cross sections for sensing applications.

Far infrared spectroscopy of mineral particles

Mineralogical characterization and far-infrared spectroscopy of laboratory analogues in the wavelength range 57 - 210 mum is performed for interpreting data from Herschelpsilas Photodetector Array Camera and Spectrometer (PACS).