Rotational-level-dependent quenching of OH A 2Σ(v′ = 1) by collisions with H2O in a low-pressure flame

✍ Scribed by Robert J. Cattolica; Thomas G. Mataga

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 752 KB
• Volume: 182
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(91)90136-w

✦ Synopsis

The collisional quenching of OH A'Z(u' = 1) by Hz0 was determined from laser-induced fluorescence measurements in the burned-gas region of stoichiometric H,/OJAr flames at low pressure ( 19 and 38 Torr). The collisional quenching was measured as a function of the initial laser-populated rotational level for N' = 4, 5, 8, 9, IO and 1 I. The quenching cross section after laser excitation to N' =4 is 32 * 2.5 A' at a temperature of 1048 K, approximately 40% of its value at room temperature. The quenching cross section decreases by 17% as the initial laser-excited rotational level is increases from IV' =4 to N' = 1 I. This variation in quenching rate has a significant effect on the determination of OH rotational temperature from laser-excitation spectra. Accounting for the variation of quenching with rotational level reduces the rotational temperature by 10% at 1100 K. The collisional quenching cross section of OH A *2( ZJ' = I ) by H atoms was calculated to be 10 + 3 A2 for N' = 5 at a temperature of IO48 K.