Chemical origins of the Mars ultraviolet dayglow.

Airglow optical emissions from planetary atmospheres provide remotely observable signatures of atmospheric composition, energy deposition processes, and the resulting chemical reactions. We may one day be able to detect airglow emissions from extrasolar planets. Reliable interpretation requires quantitative understanding of the energy sources and chemical mechanisms that produce them.

Detection of explosives and explosives-related compounds by single photon laser ionization time-of-flight mass spectrometry.

The application of single photon ionization in combination with mass-selective detection by time-of-flight mass spectrometry is described for the rapid detection of the nitro-containing explosives and explosives-related compounds nitrobenzene, 1,3-dinitrobenzene, o-nitrotoluene, 2,4-dinitrotoluene, and 2,4,6-trinitrotoluene, as well as the peroxide-based explosive triacetone triperoxide in the gas phase. The technique is demonstrated to be a plausible approach for laser-based rapid detection of explosives. The limits of detection for nitrobenzene and 2,4-dinitrotoluene using SPI were also measured and determined to be 17-24 (S/N approximately 2:1) and approximately 40 ppb (S/N approximately 2:1), respectively.

Vibrational energy transfer and relaxation in O2 and H2O.

Near-resonant vibrational energy exchange between oxygen and water molecules is an important process in the Earth's atmosphere, combustion chemistry, and the chemical oxygen iodine laser (COIL). The reactions in question are (1) O2(1) + O2(0) --> O2(0) + O2(0); (2) O2(1) + H2O(000) --> O2(0) + H2O(000); (3) O2(1) + H2O(000) <--> O2(0) + H2O(010); (4) H2O(010) + H2O(000) --> H2O(000) + H2O(000); and (5) H2O(010) + O2(0) --> H2O(000) + O2(0). Reanalysis of the data available in the chemical kinetics literature provides reliable values for rate coefficients for reactions 1 and 4 and strong evidence that reactions 2 and 5 are slow in comparison with reaction 3.