Isotope [sup.18]O/[sup.16]O ratio measurements of water vapor by use of the 950-nm wavelength region with cavity ring-down and photoacoustic spectroscopic techniques

Two optical methods, cavity ring-down spectroscopy and photoacoustic spectroscopy, are applied to the measurement of the isotope ratio [sup.18]O/[sup.16]O in water-vapor samples with a [Nd.sup.3+]:YAG pumped-dye laser. The combination band of (2[v.sub.1] + [v.sub.3]) in the 960-nm region of water molecules is investigated for two standard water samples, the Vienna Standard Mean Ocean Water and the Standard Light Antarctic Precipitation. The results demonstrate that the two methods have the potential of compact systems for in-situ measurements of [H.sub.2]O isotope ratio in the environment. OCIS codes: 300.6430, 000.2170, 010.7340, 010.1280, 020.3260, 140.2050.