Advances of sensitive techniques in laser spectroscopy

摘要

Different techniques are used for the sensitive detection of overtone transitions of small molecules, such as H2S, C2H2, OCS, O-3 in the visible and near infrared region. The techniques include: phase-modulated or wavelength-modulation absorption spectroscopy with a widely tunable single mode diode laser, opto-acoustic spectroscopy in resonance cells with a color center laser or a Ti:Sapphire laser, and sub-Doppler opto-thermal spectroscopy in cold collimated molecular beams, using a low temperature bolometer as detector. The three techniques are compared with regard to sensitivity and spectral resolution. The mass selective sensitive detection of small metal clusters Li-3 and Na-3 and their high resolution sub-Doppler spectroscopy, using resonant two-photon ionization with cw lasers, is briefly discussed. (C) 2007 Elsevier B.V. All rights reserved.