Absorptionsspektren von halogenierten Methanen im Bereich von 275 bis 160 nm bei Temperaturen von 298 und 208 K

Abstract

Die Absorptionsspektren der halogenierten Methane CCl3F, CCl2F2, CHCl2F, CHClF2 und CH3Cl wurden im Wellenlängenbereich von 275 bis 160 nm bei 298 und 208 K bestimmt.

Ultraviolet absorption cross-sections of chloro and chlorofluoro-methanes at stratospheric temperatures

“…In the case of methylene chloride (CH&), if one expects the data of Gordus and Bernstein (1954) limited to a narrow wavelength range (205-220 nm), the only available data are the values published by Hubrich and Stuhl (1980) which are, on average, 10% higher than those reported here.…”

“…Discrepancies can be explained by a critical analysis of the experimental conditions reported by Hubrich et al (1977) and Hubrich and Stuhl ( 1980) which reveals that some measurements have been performed in less favorable conditions, namely transmitted fluxes lower than 5% or higher than 95%, leading to larger uncertainties than those reported in this work for which experimental measurements for transmission below 10% and above 85% have been eliminated in order to stay in a range where the Beer-Lambert law is applicable within the quoted accuracy.…”

“…(1977) and Hubrich and Stuhl ( 1980) for only one low temperature (208 K). Their results confirm qualitatively the general conclusions mentioned above and are in fairly good agreement for CF2C12 between 190 and 205 nm (within the experimental accuracy of 4Oh) but diverge from about -5Oh at 200 nm up to k40°h at 230 nm for CFC13.…”

VUV spectroscopy of CH3Cl and CH3I

“…On the basis of ab initio optimised geometry calculations, Locht et al [20] conclude that the experimentally observed 77 ± 7 meV and 104 ± 7 meV modes are due to t 6 (CH 3 bending) and t 5 (CH 3 rocking coupled with C-Cl stretching), respectively. The 162 ± 3 meV mode is simply labelled t and is considered to represent either t 3 (anti-symmetric CH 3 bending) [43,45,46]; (b) vibrational structure associated with 4p Rydberg transitions and (c) Rydberg structure in the high-energy part of ASTRID range (over page).…”

VUV photoabsorption in CF3X (X=Cl, Br, I) fluoro-alkanes

“…The table also includes the equivalent values for CH 3 Cl and CH 3 I [60]. The errors given for the A band energies and cross-sections are estimated on the basis of comparisons with previous photoabsorption [11,30,49,65,66] and EELS [24] measurements.…”