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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >TEMPERATURE DEPENDENCE OF UV ABSORPTION CROSS SECTIONS AND ATMOSPHERIC IMPLICATIONS OF SEVERAL ALKYL IODIDES
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TEMPERATURE DEPENDENCE OF UV ABSORPTION CROSS SECTIONS AND ATMOSPHERIC IMPLICATIONS OF SEVERAL ALKYL IODIDES

机译：几种烷基碘的紫外线吸收截面的温度依赖性和大气含义

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摘要

The ultraviolet absorption spectra of a number of alkyl iodides which have been found in the troposphere, CH3I, C2H5I, CH3CH2CH2I, CH3CHICH3, CH2I2, and CH2ClI, have been measured over the wavelength range 200-380 nm and at temperatures between 298 and 210 K. The absorption spectra of the monoiodides CH3I, C2H5I, CH3CH2CH2I, and CH3CHICH3 are nearly identical in shape and magnitude and consist of single broad bands centered near 260 nn. The addition of a chlorine atom in CH2ClI shifts its spectrum to longer wavelengths (sigma(max) at 270 nm). The spectrum of CH2I2 is further red-shifted, reaching a maximum of 3.85 x 10(-18) cm(2) molecule(-1) at 288 nm and exhibiting strong absorption in the solar actinic region, lambda>290 nm. Atmospheric photolysis rate constants, J values, have been calculated assuming quantum efficiencies of unity for different solar zenith angles as a function of altitude using the newly measured cross sections. Surface photolysis rate constants. calculated from the absorption cross sections measured at 298 K, range from 3 x 10(-6)s(-1) for CH3I to 5 x 10(-3)s(-1) for CH2I2 at a solar zenith angle of 40 degrees. [References: 39]
机译：在对流层CH3I，C2H5I，CH3CH2CH2I，CH3CHICH3，CH2I2和CH2ClI中发现了许多烷基碘的紫外吸收光谱，测量的波长范围为200-380 nm，温度为298至210 K单碘化物CH3I，C2H5I，CH3CH2CH2I和CH3CHICH3的吸收光谱在形状和大小上几乎相同，并由中心在260 nn附近的单个宽带组成。在CH2ClI中添加氯原子会将其光谱移动到更长的波长（270 nm的sigma（max））。 CH2I2的光谱进一步红移，在288 nm处最大达到3.85 x 10（-18）cm（2）分子（-1），并在λ> 290 nm的太阳光化区域表现出较强的吸收。使用新测量的横截面，假设不同太阳天顶角的单位量子效率与海拔高度有关，计算出大气光解速率常数J值。表面光解速率常数。根据在298 K下测量的吸收截面计算得出，在40度太阳天顶角下，CH3I的范围为3 x 10（-6）s（-1），CH2I2的范围为5 x 10（-3）s（-1） 。 [参考：39]

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