Tunable diode laser spectrometry

Sauke, T.B. Becker, J.F. Loewenstein, M. Gutierrez, T.D. 8c Bratton, C.G., An Overview of Isotope Analysis Using Tunable Diode Laser Spectrometry Spectroscopy 1994, 9(5), 34-39. 

Stacknik et al, 1992), and by in-situ tunable diode laser spectrometry (May and Webster, 1989). In the 1990s, global distributions of this gas were obtained by the HALOE infrared instrument aboard UARS (Russell et al., 1993 Figure 5.59). The distribution and variability of the total column abundances of HC1 have been reported, for example, by Mankin and Coffey (1983). 

Ab initio calculations have been made of the vibrational wavenumbers of the radicals XSO and XSO2 (X = F or Cl) in the ground and excited states. Tunable diode laser spectrometry gave data on line intensities for the V1+V3 band of S02. Revised vibrational assignments have been proposed for the fluorosul-fite ion, S02F. Values for the Cs salt are given in in Table 18. ... 

The instrumentation on board the Citation aircraft has been described by J. Lelieveld et al. [Geophysical Research Letters, 104 8201 (1999)]. On the Citation, C-130 air-craft, and the RW Brown, CH3CN and CH3C(0)CH3 have been measured by proton-transfer-reaction mass spectrometiy, as described by W. Lindinger, A. Hansel, and A. Jordan [International Journal of Mass Spectrometry and Ion Processes, 173 191 (1998)]. On the C-130 aircraft, these gases and SO2 were also measured by chemical ionization mass spectrometry. On the Citation aircraft, CO was measured by tunable diode laser spectrometry (TDLAS), as described by F.G. Wienhold et al. [Journal of Applied Physics, B67 411 (1998)] on the RW Brown, CO was measured by TDLAS, as described by H. Fischer et al. [Journal of Geophysical Research, 102 23559 (1997)]. 

Vapour pressures for a number of atmospherically relevant condensed systems have been measured with mass spectrometry. These systems include hydrates of HC1, HjS04 and HNO, supercooled liquids and pure water-ice, as well as the interactions of HC1 vapour with die solids, ice and NAT [23,47,50-55]. Vapour pressure measurements over HNOj/HjO hydrates have also been made using infrared optical absorption with light originating from a tunable diode laser [29]. This technique allowed the identification of the metastable NAD in presence of the more stable NAT under temperature and vapour pressure conditions near to those found in the polar stratosphere. Vapour pressures of Up, HN03, HC1, HBr over supercooled aqueous mixtures with sulfuric acid have been calculated using an activity model [56]. It provides a parameterized model for vapour pressures over the stratospheric relevant temperatures (185-235 K). 

The advantages of Tunable Diode Laser Absorption Spectrometry (TDLAS) for measuring trace atmospheric gases are universality positive identification good sensitivity and rapid response time. An instrument is described which can measure two gases simultaneously under automatic computer control with detection limits better than 100 parts per trillion and with response times better than 5 minutes. Procedures have been established for the measurement of NO N0a, HNOa NH3 HbQb and HCHO. These species have been measured under a variety of conditions in smog chambers and in ambient air from mobile laboratories and from aircraft. 

F1g.7.5. Schematic diagram of a tunable diode laser instrument for high-resolution spectrometry (Courtesy Spectra Physics)... 

HONO by mass spectrometry at 226 and 300 K. Streit et al. used tunable diode laser spectroscopy to monitor the decay of HONO in the presence of ozone at 296 K. 

Diode laser sources Already in 1980, lasers had been suggested as excitation sources for atomic absorption spectrometry [11]. Tunable dye lasers can provide virtually any atomic hne between 213 and 900 run with a bandwith corresponding to the natural hne width of an atomic hne and with a comparatively high intensity. However, they have not found widespread acceptance for this apphcation so far due to their cost and complex operation compared to hollow cathode or electrodeless discharge lamps. This situation seems to have changed with the advent of inexpensive, mass produced diode lasers (DL) [12, 13]. 

Tunable lasers (preferentially dye lasers and diode lasers) are used as primary sources for atomic absorption spectroscopy with various atomizers such as flames, furnaces, or plasmas LAAS laser atomic absorption spectrometry CRS cavity ring-down spectroscopy... 

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