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苯乙腈广泛应用于医药、农药、染料、光电材料和喹啉衍生物的合成, 在相关领域备受关注. 本文采用超声分子束技术获得了苯乙腈的单色共振双光子电离光谱, 确定了该分子的激发能为(37646 ± 2) cm –1. 结合密度泛函理论计算和Franck-Condon模拟, 详细分析了测量的振动频率, 给出了尽可能准确的光谱归属. 理论和实验结果都表明, 光谱的低频区域信号强、背景低、分辨率好, 而高频范围表现出相反特征. 许多谱带被确认, 大部分属于芳香环平面内的振动, 理论计算表明这与跃迁过程中芳香环的扩张有关.
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关键词:
- 苯乙腈/
- 单色共振增强双光子电离光谱/
- Franck-Condon模拟/
- 振动频率
Phenylacetonitrile (PAN) is widely used in the synthesis of medicines, pesticides, dyes, optoelectronic materials and quinoline derivatives, and has attracted much attention in related fields. In this paper, we report the one-color resonance enhanced two-photon ionization spectra of PAN obtained with ultrasonic molecular beam technique for the first time. The band origin of the S 1← S 0electronic transition is determined to be (37646 ± 2) cm –1. Density functional theory B3LYP/6-311G++(d, p) and B3LYP/aug-cc-pvtz are used to calculate the structures, energy and vibrational frequencies of the molecule. Based on these calculations Franck-Condon spectral simulations are performed. The measured vibrational frequencies are analyzed in detail. Combined with theoretical calculation, the spectral assignments are given as accurately as possible. Theoretical and experimental results are in good agreement with each other, and show that the spectrum in the low frequency region has a great signal-noise ratio and resolution, while in the high frequency region the spectrum shows opposite characteristics, revealing that the high background in high frequency region originates from dense and weak overtone and combined vibrations. Many spectral bands are found, and most of them may be assigned to the in-plane ring deformation, and theoretical calculations suggest that this is related to the expansion of the aromatic ring during the transition.-
Keywords:
- phenylacetonitrile/
- one-color resonance enhanced two-photon ionization spectroscopy/
- Franck-Condon simulation/
- vibrational frequency
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] -
跃迁能 实验a) 相对强度 振动频率b) 振动频率c) 模式归属d) Ire) 37646 0 100 — — $ {0}_{0}^{0} $, band origin — 37690 44 2 29 39 γ$ {{\text{CH}}_{2}}_{0}^{1} $ — 37770 124 19 125 125 $ {\beta {\rm{C}}{{\rm{H}}}_{2}\text{CN}}_{0}^{1}{\text{CN}}_{0}^{1} $ — 37920 247 1 239 249 $ {\beta {\rm{C}}{{\rm{H}}}_{2}\text{CN}}_{0}^{2}{\text{CN}}_{0}^{2} $ — 37971 398 29 393 392 $ 6{a}_{0}^{1} $ — 38111 465 2 454 460 $ 16{a}_{0}^{1} $ — 38175 529 73 527 526 $ 6{b}_{0}^{1} $ — 38207 561 22 562 563 β$ {\text{CN}}_{0}^{1} $ — 38298 652 5 652 651 $ 6{b}_{0}^{1}{\beta {\rm{C}}{{\rm{H}}}_{2}\text{CN}}_{0}^{1} $ — 38402 756 46 757 758 $ {1}_{0}^{1} $ — 38477 831 3 840 836 $ {1}_{0}^{1}{\gamma {\rm{C}}{{\rm{H}}}_{2}}_{0}^{2} $ — 38525 879 11 882 883 $ {1}_{0}^{1}{\beta {\rm{C}}{{\rm{H}}}_{2}{\rm{C}}{\rm{N}}}_{0}^{1}{1}_{0}^{1}{\gamma {\rm{C}}{{\rm{H}}}_{2}{\rm{C}}{\rm{N}}}_{0}^{1} $ — 38568 922 66 922 921 ${\nu \text{C-CN} }_{0}^{1}$ 940 38598 952 29 947 948 $ 18{a}_{0}^{1} $ 969 38604 958 30 946 955 β$ {\text{CN}}_{0}^{1}6{a}_{0}^{1} $ 988 38617 971 18 962 966 $ {12}_{0}^{1} $ 1003 38690 1044 4 1047 1044 $ {12}_{0}^{1}{\gamma {\rm{C}}{{\rm{H}}}_{2}}_{0}^{2} $ 1029 38800 1154 24 1154 1156 $ {13}_{0}^{1} $ 1076 38812 1166 5 1155 1170 $ {11}_{0}^{2} $ 1157 38856 1210 3 1201 1215 $ {12}_{0}^{1}{10 b}_{0}^{2} $ 1184 38878 1232 8 1233 1234 $ {13}_{0}^{1}\text{g}{{{\rm{C}}{\rm{H}}}_{2}}_{0}^{2}{13}_{0}^{1}\text{g}{{{\rm{C}}{\rm{H}}}_{2}}_{0}^{1} $ 1203 38913 1267 18 1254 1255 ${\nu \text{C-C}{\text{H} }_{2}\text{CN} }_{0}^{1}$ — 38934 1288 17 1284 1285 $ {\text{1}}_{0}^{1}6{b}_{0}^{1} $ — 38963 1317 12 1315 1313 ${\nu \text{C-CN} }_{0}^{1}6{a}_{0}^{1}$ — 38969 1323 13 1319 1321 $ {1}_{0}^{1} $β$ {\text{CN}}_{0}^{1} $ 1336 38998 1352 5 1347 1353 $ {1}_{0}^{1}16{b}_{0}^{2} $ — 39004 1358 9 1355 1358 $ {12}_{0}^{1}6{a}_{0}^{1} $ — 39065 1419 6 1417 1418 $ {18 a}_{0}^{1}6{a}_{0}^{1}\text{g}{{{\rm{C}}{\rm{H}}}_{2}}_{0}^{2} $ 1415 39096 1450 21 1448 1447 ${\nu \text{C-CN} }_{0}^{1}6{b}_{0}^{1}$ 1454 39100 1454 34 1453 1452 $ 9{b}_{0}^{1}{\text{15}}_{0}^{1} $ — 39108 1462 12 1466 1465 $ 18{a}_{0}^{1}6{a}_{0}^{1}{\beta \text{C}{\text{H}}_{2}\text{CN}}_{0}^{1} $ — 39129 1483 17 1474 1474 $ {18 a}_{0}^{1}6{b}_{0}^{1} $ 1495 39146 1500 14 1507 1504 $ 8{b}_{0}^{1} $ — 39154 1508 7 1509 1511 $ {18 a}_{0}^{1}\text{b}{{\rm{C}}{\rm{N}}}_{0}^{1} $ — 39162 1516 7 1514 1518 $ {1}_{0}^{2} $ — 39182 1536 4 1536 1542 $ 8{a}_{0}^{1}16{b}_{0}^{2} $ — 39200 1554 6 1547 1549 $ {13}_{0}^{1}6{a}_{0}^{1} $ 1586 39217 1571 5 1546 1569 $ {12}_{0}^{1}6{b}_{0}^{1}\text{g}{{{\rm{C}}{\rm{H}}}_{2}}_{0}^{2} $ 1602 39328 1682 23 1680 1682 $ {13}_{0}^{1}6{b}_{0}^{1} $ — 39347 1701 11 1704 1707 $ {18 a}_{0}^{1}{1}_{0}^{1} $ — 39360 1714 3 1716 1719 $ {13}_{0}^{1}\text{b}{{\rm{C}}{\rm{N}}}_{0}^{1} $ — 39376 1730 5 1719 1725 $ {12}_{0}^{1}{1}_{0}^{1} $ — 注: a) 实验振动频率是相对PAN分子的激发能(37646 cm–1)的偏移;
b) 理论计算的振动频率来自于B3 LYP/6-311++G(d, p)方法, 修正因子为0.9726;
c) 理论计算的振动频率来自于B3 LYP/aug-cc-pvtz方法, 修正因子为0.9719;
d)β, 平面内的摇摆;γ, 垂直于环平面的振动;ν, 伸缩振动;
e) 文献[8]采用红外光谱技术测量的电子基态的振动频率.
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S1 S0 Δ(S1—S0) 键长/Å (1 Å = 10–10m) C1—C2 1.42782 1.39911 0.029 C2—C3 1.42328 1.39148 0.032 C3—C4 1.42189 1.39573 0.026 C4—C5 1.42347 1.39512 0.028 C5—C6 1.41949 1.39168 0.028 C6—C1 1.42844 1.39447 0.034 C1—C12 1.50237 1.52486 –0.022 C2—H7 1.08300 1.08578 –0.003 C3—H8 1.08215 1.08413 –0.002 C4—H9 1.08270 1.08396 –0.001 C5—H10 1.08163 1.08406 –0.002 C6—H11 1.08220 1.08399 –0.002 C12—H13 1.10245 1.09555 0.007 C12—H14 1.10245 1.09555 0.007 C12—C15 1.45868 1.46019 –0.002 C15—N16 1.15351 1.15280 0.001 键角/(°) C1—C12—
C15115.76127 115.06386 0.697 C12—C15—
N16179.02074 179.70812 –0.687 下载:
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[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33]
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