Abstract

A high-resolution UV spectrum of benzaldehyde vapor is obtained in the region of 26 600–28 500 cm⁻¹ at a high temperature (140°C). An analysis is performed of the permitted vibrational structure of the bands of n–π* transmission in the UV spectrum. It is found that the UV spectrum of benzaldehyde vapors consists of 60 absorption bands. The reliability of the frequencies of 0–\({v}\) transitions of torsional vibration in the ground (S₀) and excited (S₁) electronic states is confirmed by their multiple repetition in the Deslandres tables (DTs) on the 0–0 band and the frequencies of vibration of the S₁ state (cm^–1): \(\nu {\kern 1pt} '\) = 728, 1091, and 1315. The 0–0 band for benzaldehyde corresponds to 26 912.8 cm⁻¹. The frequency of the torsional vibration of this molecule (111.2 ± 0.4 cm⁻¹) in the S₀ state is determined, and the frequencies of transition of 0–\({v}\) torsional vibrations in the S₀ state are determined up to a high value of vibrational quantum number: \({v}\) = 7. The frequency of the torsional vibrations of benzaldehyde (138.0 ± 0.4 cm⁻¹) and that of the 0–\({v}\) transitions of torsional vibration up to \({v}\) = 6 are also determined from the constructed DTs in analyzing the vibrational structure of the UV spectrum for the S₁ state. Harmonic frequencies ω_e and coefficients x₁₁ of torsional vibration anharmonicity are found for both electronic states. A total assignment of 60 bands of vibrational structure was carried out.

中文翻译：

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气相中苯甲醛的高分辨率紫外吸收光谱的振动结构

摘要

甲在26 600-28500厘米的区域中获得的苯甲醛蒸气的高分辨率UV光谱^-1在高温下（140℃）。对紫外光谱中n –π *传输带的允许振动结构进行了分析。发现苯甲醛蒸气的UV光谱由60个吸收带组成。在地面（S ₀）和受激（S ₁）电子状态下，扭转振动的0– \（{v} \）跃迁频率的可靠性通过在0的Deslandres表（DTs）中的多次重复来证实。 –0频带和S ₁状态的振动频率（cm ^–1）：\（\ nu {\ kern 1pt}'\） = 728、1091和1315。苯甲醛的0-0谱带对应于26 912.8 cm ^-1。该分子（111.2±0.4厘米的扭转振动的频率^-1）在小号₀状态被确定，和0-过渡的频率\（{V} \）在扭转振动小号₀状态被确定了到较高的振动量子数：\（{v} \） =7。苯甲醛的扭转振动频率（138.0±0.4 cm ^-1）和0– \（{v} \）跃迁的频率扭转振动高达\（{v} \）在分析S ₁状态的UV光谱的振动结构时，还从构造的DT中确定= 6 。谐波频率ω _Ë和系数X ₁₁扭转振动的非谐性被发现两者的电子态。总共分配了60条振动结构。