Laser enhanced ionization detector for Raman spectroscopy

摘要

Raman spectroscopy uses a resonance ionization detector. In particular, a first laser source is provided for application of laser energy to a sample cell. A second laser source provides energy to the ionization detector, which ionization detector includes metal vapor having at least three energy states or levels. The laser from the second laser source has a frequency such that it will promote the metal vapor from one of its levels to a higher level, whereas the first laser source is tunable such that upon Raman scatter from the sample cell promoting the metal vapor as well, the metal atoms will be ionized and the ionization detector will detect the scatter from the sample material. The scatter from the sample cell is provided to the ionization detector by way of an optical coupler such as a lens. The ionization detector may be a flame-type ionization detector, a metal vapor cell ionization detector, for a glow discharge tube (such as a hollow cathode lamp) ionization detector.