High-resolution absorption studies of the A(1)A2-X(1)A1 2(0)(2)4(0)(1) band of formaldehyde.
High-resolution absorption studies of the A(1)A2-X(1)A1 2(0)(2)4(0)(1) band of formaldehyde.
复制标题
甲醛 A(1)A2-X(1)A1 2(0)(2)4(0)(1) 谱带的高分辨率吸收研究。
DOI：
10.1021/jp9023475
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
Crow MB
中科院分区：
文献类型：
--
作者：
Crow MB
绝对峰值吸收截面和压力加宽系数已被记录与亚多普勒有限的仪器分辨率为选定的旋转线在202401振动带的甲醛A 1A 2-X 1A 1电子跃迁。测得的吸收截面范围在（0.18 ± 0.01）和（10.1 ± 0.08）× 10− 19 cm 2 molecule − 1之间，并且比文献中使用仪器显着增宽的仪器记录的值大得多。然而，与Smith等人（J. Phys. Chem. A2006，110，11645 - 11653）的具有相同分辨率的光谱模拟进行比较，结果非常一致。研究了碰撞伙伴CH 2 O，CO2，N2，O2，Ne，Kr，Ar和He的压力展宽，并发现由此产生的展宽系数相比，在红外区域测量的等效值减少，与减少的偶极矩在这项工作中探测的上部状态相一致。腔增强吸收光谱（CEAS）测量使用来自渗透源的校准低浓度（2.9−4.6 ppmv）样品进行，并证明噪声等效吸收为1.2 × 10−6cm−1Hz−1/2。这意味着当前系统在大气中的最小可检测甲醛浓度为172 ppbv Hz−1/2。
Absolute peak absorption cross sections and pressure broadening coefficients have been recorded with sub-Doppler limited instrumental resolution for selected rotational lines in the 202401vibronic band of the formaldehyde Ã1A2−X̃1A1electronic transition. The measured absorption cross sections range between (0.18 ± 0.01) and (10.1 ± 0.08) × 10−19cm2molecule−1and are considerably larger than values from the literature recorded using apparatus where instrumental broadening was significant. However, comparisons with spectral simulations with equivalent resolution from Smith et al. (J. Phys. Chem. A2006,110, 11645−11653) are in excellent agreement. Pressure broadening was studied for the collision partners CH2O, CO2, N2, O2, Ne, Kr, Ar, and He, and the resulting broadening coefficients were found to be reduced in comparison to equivalent values measured in infrared regions, consistent with the reduced dipole moment of the upper state probed in this work. Cavity-enhanced absorption spectroscopy (CEAS) measurements were undertaken using calibrated low concentration (2.9−4.6 ppmv) samples from a permeation source and demonstrate a noise equivalent absorption of 1.2 × 10−6cm−1Hz−1/2. This implies a minimum detectable formaldehyde concentration with the current system in atmospheric air of 172 ppbv Hz−1/2.