Abstract-Amino acid analyses of the Antarctic CM2 chondrites Allan Hills (ALH) 83100 and Lewis Cliff (LEW) 90500 using liquid chromatography-time of flight-mass spectrometry (LC-ToF-MS) coupled with UV fluorescence detection revealed that these carbonaceous meteorites contain a suite of indigenous amino acids not present in Antarctic ice. Several amino acids were detected in ALH 83100, including glycine, alanine, β-alanine, γ-amino-n-butyric acid (γ-ABA), and α-aminoisobutyric acid (AIB) with concentrations ranging from 250 to 340 parts per billion (ppb). In contrast to ALH 83100, the CM2 meteorites LEW 90500 and Murchison had a much higher total abundance of these amino acids (440-3200 ppb). In addition, ALH 83100 was found to have lower abundances of the α-dialkyl amino acids AIB and isovaline than LEW 90500 and Murchison. There are three possible explanations for the depleted amino acid content in ALH 83100: 1) amino acid leaching from ALH 83100 during exposure to Antarctic ice meltwater, 2) a higher degree of aqueous alteration on the ALH 83100 parent body, or 3) ALH 83100 originated on a chemically distinct parent body from the other two CM2 meteorites. The high relative abundance of ε-amino-n-caproic acid (EACA) in the ALH 83100 meteorite as well as the Antarctic ice indicates that Nylon-6 contamination from the Antarctic sample storage bags may have occurred during collection.

A transportable prototype Faraday rotation spectroscopic system based on a tunable external cavity quantum cascade laser has been developed for ultrasensitive detection of nitric oxide (NO). A broadly tunable laser source allows targeting the optimum Q 3/2(3/2) molecular transition at 1875.81 cm ؊1 of the NO fundamental band. For an active optical path of 44 cm and 1-s lock-in time constant minimum NO detection limits (1) of 4.3 parts per billion by volume (ppbv) and 0.38 ppbv are obtained by using a thermoelectrically cooled mercury-cadmium-telluride photodetector and liquid nitrogen-cooled indium-antimonide photodetector, respectively. Laboratory performance evaluation and results of continuous, unattended monitoring of atmospheric NO concentration levels are reported.external cavity laser ͉ nitric oxide detection ͉ midinfrared ͉ magnetic circular birefringence ͉ paramagnetic species I n this article, we describe the development and performance of a prototype transportable, cryogen-free spectroscopic sensing system for ultrasensitive detection of atmospheric nitric oxide (NO) based on Faraday rotation spectroscopy (FRS). The FRS technique as a method for improving sensitivity by reducing source noise was first reported in the 1980s with a color-center laser source (1). The recent availability of thermoelectrically cooled widely tunable continuous wave (CW) external cavity quantum cascade lasers (EC-QCLs) (2) makes feasible a transportable FRS NO sensor targeting the optimum Q 3/2 (3/2) NO absorption line of the fundamental vibration at 5.33 m that has great potential for development into a compact field-deployable system. Ultrasensitive trace gas detection is of increasing interest in various applications including environmental monitoring, industrial emission measurements, chemical analysis, medical diagnostics, and security. The combination of midinfrared, continuous wave, high-performance QCL sources with sensitive spectroscopic measurement techniques is leading to improved specificity, and lower minimum detection limits (MDLs) for many molecular species as compared with nonoptical chemical sensors. This work was made possible by recent advances in QCL fabrication technology that have resulted in Fabry-Perot QC laser chips with wide gain bandwidth and high-output power levels at room temperature (3). These developments permit the construction of widely tunable EC-QCLs like the one used here.Our development of an EC-QCL-based FRS spectrometer was motivated by the current need for monitoring and quantifying the significant increase of atmospheric NO concentration levels due to combustion emissions that are impacting air quality in urban environments worldwide. NO molecules play a major role in atmospheric chemistry and significantly contribute to the formation of photochemical smog and acid rain and to the depletion of the stratospheric ozone layer (4, 5). Furthermore, NO at low concentrations in human and mammalian cells is of great importance in the regulation of biological and physiological processes (6). ...

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We report a laser spectroscopy technique for detecting optical absorption in gases and micro-objects via linked thermal effects and by using a sharp mechanical resonance in a quartz crystal. The performance of this technique is studied using near-IR diode lasers and two gases, pure CO(2) and C(2)H(2) diluted in nitrogen. A 7.3 × 10(-8) cm(-1)W/(Hz)(1/2) noise equivalent sensitivity to absorption in gases is demonstrated. Based on experimental results, it was estimated that 10(-8) fractional absorption of optical radiation by a micro-object deposited on a thin transparent fiber can be detected.

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