Isotope (18)O/(16)O Ratio Measurements of Water Vapor by use of Photoacoustic Spectroscopy.
We applied a photoacoustic spectroscopy technique to isotope ratio measurements of (16)O and (18)O in water-vapor samples, using a pulsed tunable dye laser pumped by a Nd:YAG laser. The fourth overtone bands (4nu(OH)) of water molecules near 720 nm were investigated. We identified the absorption lines of H(2)(16)O and H(2)(18)O in the photoacoustic spectra that we measured by using an (18)O-enriched water sample and the HITRAN database. We measured the difference in the (18)O/(16)O isotope ratios for normal distilled water and Antarctic ice, using the photoacoustic method. The value obtained for the difference between the two samples is delta(18)O = -32 ? 16 per thousand, where the indicated deviation was a 1varsigma value among 240-s measurements, whereas the value measured with a conventional isotope mass spectrometer was delta(18)O = -28 ? 2 per thousand. This method is demonstrated to have the potential of a transportable system for in situ and quick measurements of the H(2)(18)O/H(2)(16)O ratio in the environment.
Matsumi
Y
Y
Kishigami
M
M
Tanaka
N
N
Kawasaki
M
M
Inoue
G
G