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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Utraviolet-Visible Absorption Cross Sections of Gaseous HOBr
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Utraviolet-Visible Absorption Cross Sections of Gaseous HOBr

机译：气态HOBr的紫外可见吸收截面

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摘要

The UV-visible absorption cross sections for HOBr between 260 and 545 nm have been measured at 295 K in either 80 or 300 Torr of He bath gas. HOBr was generated in situ by laser photolytic production of OH radicals in the presence of Br↓(2), and its absorption of light was detected using both a gated diode array camera (220 nm windows) and a photomultiplier. Calibration was performed relative to Bt2 loss. The UV-visible spectrum of HOBr consists of three broad absorption bands between about 240 and 550 nm, with λ↓(max) at 284 nm (fy = (25.0 ± 1.2) × 10↑(-20) cm↑(2)), 351 nm (σ = (12.4 ± 0.6) × 10↑(-20) ↑(2)), and 457 nm (o = (2.3 ± 0.2) × 10-↑(-20) cm↑(2)). The existence of the third, long-wavelength absorption band has been confirmed unambiguously in this work. J-value calculations show that absorption into the third band is responsible for up to 50% of the total photolysis rate at high zenith angles close to the surface and at least 25% at all other altitudes and zenith angles down to 40°. At this zenith angle the total J value ranges from 3.2× 10↑(-3) s↑(-1) at 15 km to 2.2 ×10↑(-3) s↑(-1) a at the surface, corresponding to lifetimes of 5.2 and 7.6 min, respectively.
机译：在295 K下，在80或300 Torr的He浴气体中测量了HOBr在260至545 nm之间的紫外可见吸收截面。在Br↓（2）存在下，通过激光光解OH自由基原位生成HOBr，并使用门控二极管阵列相机（220 nm窗口）和光电倍增管检测其光吸收。相对于Bt 2损失进行校准。 HOBr的紫外可见光谱由约240至550 nm之间的三个宽吸收带组成，λ↓（max）在284 nm处（fy =（25.0±1.2）×10↑（-20）cm↑（2）） ，351 nm（σ=（12.4±0.6）×10↑（-20）↑（2））和457 nm（o =（2.3±0.2）×10-↑（-20）cm↑（2））。这项工作明确地证实了第三长波吸收带的存在。 J值计算表明，在接近表面的高天顶角下，吸收到第三波段的光占总光解速率的50％，而在所有其他高度和低至40°的天顶角至少占25％。在此天顶角下，总J值从15 km处的3.2×10↑（-3）s↑（-1）到表面处的2.2×10↑（-3）s↑（-1）a，对应于寿命分别为5.2分钟和7.6分钟。

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