Raman spectroscopic study of CO2-NaCl-H2O mixtures in synthetic fluid inclusions at high temperatures

Mixtures of CO2-NaCl-H2O contained in synthetic fluid inclusions are studied by laser Raman spectroscopy at high temperatures. With increasing temperature, the band splitting (X) of nu(1)-2nu(2) diad of spectrum of CO2 presents more variations, and the intensity ratios of the hot bands to the nu(1)-2nu(2) diad increase. For mixtures of gas phase rich in CO2 and liquid phase rich in H2O before homogenization, the strength of hydrogen bonding of water in the liquid phase decreases almost linearly with increasing temperature. When mixtures become homogeneous liquid phases, carbon dioxide content increases significantly as a result of the abrupt decrease in hydrogen bonds. Our results show that the hydrogen bonds change only slightly at higher temperatures above the homogeneous point, and a certain extent of the hydrogen bonds still remains at the highest temperature of 550degreesC of this work. The study is helpful to Raman spectroscopic analysis of natural fluid inclusions at high temperatures. Copyright (C) 2004 Elsevier Ltd.