High Sensitivity Spectroscopy with Tunable Diode Lasers — Detection of O2 Quadrupole Transitions and 14C
In recent years, tunable lead-salt diode lasers (TDLs) have found widespread application in all fields of infrared spectroscopy. However, most applications of TDLs utilise only the tunability and high resolution of these devices, and few experiments have employed the ability of the TDL to detect very small absorption coefficients. We have developed a laser absorption spectrometer (LAS) which can detect absorption coefficients as small as 10−6 to l0−7 m−1, while retaining the full tunability and resolution of the TDL. This instrument has been used as a point monitoring system for many trace gases of atmospheric significance [l–3]. In this paper, we describe two additional applications of the LAS: (i) the detection of very weak transitions such as quadrupole lines in oxygen, and (ii) the detection of rare isotopes, with 14C in CO2 as an example. Details are given in the following sections.
KeywordsQuadrupole Transition Rare Isotope Multipass Cell Heat Sink Temperature Small Absorption Coefficient
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- 6.J. Reid, R.L. Sinclair, A.M. Robinson, and A.R.W. McKellar: Phys. Rev. A, in press.Google Scholar