کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5430017 | 1508705 | 2009 | 17 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: IR absorption spectrum (4200-3100 cmâ1) of H2O and (H2O)2 in CCl4. Estimates of the equilibrium constant and evidence that the atmospheric water absorption continuum is due to the water dimer IR absorption spectrum (4200-3100 cmâ1) of H2O and (H2O)2 in CCl4. Estimates of the equilibrium constant and evidence that the atmospheric water absorption continuum is due to the water dimer](/preview/png/5430017.png)
IR absorption spectra, 4200-3100Â cmâ1, of water in CCl4 solutions are presented. It is shown that for saturated solutions significant amounts of water are present as dimer (ca. 2%). The IR spectra of the monomer and dimer are retrieved. The integrated absorption coefficients of the monomer absorption are significantly enhanced relative to the gas phase values. The dimer spectrum consists of 5 bands, of which 4 were expected from data from cold beams and cold matrices. The origin of the “extra” band is discussed. In addition it is argued that the dimer absorption bands intensities must be enhanced relative to the gas phase values. Based on recent calculations of band strengths, and observed frequency shifts relative to the gas phase, the intensity enhancement factors are estimated as well as the monomer/dimer equilibrium constant in CCl4 solution at T=296Â K (Kc=1.29Â molâ1Â L). It is noted that the observed dimer spectrum has a striking resemblance with the water vapour continuum determined by Burch in 1985 which was recently remeasured by Paynter et al. and it is concluded that the atmospheric water absorption continuum in the investigated spectral region must be due to water dimer. Based on the newly published spectral data a revised value of the gas phase equilibrium constant is suggested (Kp=0.035Â atmâ1 at T=296Â K) as well as a value for the standard enthalpy of formation, ÎH0=15.4Â kJÂ molâ1.
Journal: Journal of Quantitative Spectroscopy and Radiative Transfer - Volume 110, Issue 18, December 2009, Pages 2060-2076