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六氟化硫(SF6)在电力、电子工业上有着广泛应用, 其同时是一种重要的温室气体. 研究含SF6的弱束缚复合物的光谱和结构对深入了解SF6和其他分子之间的相互作用具有重要意义. 本文利用基于量子级联激光器的直接吸收光谱技术, 测量了SF6/Ar/He混合气体在10.6 μm处的超声射流冷却红外光谱. 除了32SF6-Ar的平行和垂直振动谱带外, 还观测到一个新的复合物振动谱带. 这个新谱带被初步归属为32SF6-34SF6复合物的32SF6单元的振动激发, 也是一个垂直振动谱带. 对32SF6-Ar和32SF6-34SF6的垂直振动谱带进行了转动分析, 得到了精确的振动带心和转动常数等分子参数.
Sulfur hexafluoride (SF6) is widely used in the electrical and electronic industries. It is also an important green-house gas. The study of spectra and structures of weakly bound complexes containing SF6 is helpful to gain a deep understanding of the intermolecular interactions between SF6 and other atoms or molecules. The rotationally resolved spectrum of the perpendicular vibrational band of 32SF6-Ar in the 32SF6 v3 band region has been reported previously but the rotational analysis was not completed. In this work, this vibrational band of 32SF6-Ar is re-investigated. The jet-cooled rovibrational spectra of SF6/Ar/He gas mixtures are measured by a continuous-wave distributed feed-back quantum cascade laser (DFB-QCL) at 10.6 μm with a segmented- rapid-scan data acquisition scheme. The gas mixture (SF6∶Ar∶He = 0.12∶1∶100) is expanded into a cylinder vacuum chamber through a 0.8 mm pin-hole nozzle. The probe laser is reflected about 90 times by a pair of astigmatic mirrors inside the chamber. The observed spectrum is analyzed by the standard symmetric-top Hamiltonian with the program PGOPHER. When the resonance interaction between the l = $ \pm 1 $ levels in the double-degenerate excited vibrational state of 32SF6-Ar is considered, which was ignored in previous studies, a successful rotational analysis of the perpendicular vibrational band is conducted. The band-origin of the perpendicular band is determined to be v0 = 947.45300(58) cm–1 and the resonance interaction parameter is q = –0.002325(70) cm–1. A set of absorption lines close to the Q branch of the 32SF6 v3 band is tentatively assigned to the perpendicular vibrational band of 32SF6-34SF6 complex. This band is heavily overlapped by the monomer lines so that very few lines can be assigned. The band-origin of this band is estimated to be 948.1181(12) cm–1. These results will be useful for developing highly accurate intermolecular potential energy surfaces for SF6-Ar complex and SF6 dimer in the future. [1] Makarov G N 2005 Phys. -Usp. 48 37
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[2] Zellweger J M, Philippoz J M, Melinon P, Monot, van den Bergh H 1984 Phys. Rev. Lett. 52 522
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[3] Eerkens J W 1998 Laser Part. Beams 16 295
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[4] Makarov G N 2015 Phys. -Usp. 58 670
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[5] 李业军, 郭静, 马俊平, 唐显, 李鑫, 闫冰 2022 物理学报 71 243401
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Li Y G, Guo J, Ma J P, Tang X, Li X, Yan B 2022 Acta Phys. Sin. 71 243401
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[6] Geraedts J, Setiadi S, Stolte S, Reuss J 1981 Chem. Phys. Lett. 78 277
Google Scholar
[7] Geraedts J, Stolte S, Reuss J 1982 Zeit. Phys. A 304 167
Google Scholar
[8] Urban R D, Takami M 1995 J. Chem. Phys. 103 9132
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[9] Asselin P, Potapov A, Turner A C, Boudon V, Bruel L, Gaveau M A, Mons M 2017 Phy. Chem. Chem. Phys. 19 17224
Google Scholar
[10] Kolomiitsova T D, Mielke Z, Shchepkin D N, Tokhadze K G 2002 Chem. Phys. Lett. 357 181
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[11] Tokhadze I K, Kolomiitsova T D, Shchepkin D N, Tokhadze K G, Mielke Z 2009 J. Phys. Chem. A 113 6334
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[12] van Bladel J W I, van der Avoird A 1990 J. Chem. Phys. 92 2837
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[13] Vazhappilly T, Marjolin A, Jordan K J 2016 J. Phys. Chem. B 120 1788
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[14] Hartmann M, Miller R E, Toennies J P, Vilesov A F 1996 Science 272 1631
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[15] Asselin P, Turner A C, Bruel L, Brenner V, Gaveau M A, Mons M 2018 Phy. Chem. Chem. Phys. 20 28105
Google Scholar
[16] Luo W, Zhang Y L, Li W G, Duan C X 2017 J. Mol. Spectrosc. 334 22
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[17] 袁洪瑞, 刘涛, 朱天鑫, 刘云, 李响, 陈杨, 段传喜 2023 物理学报 72 063301
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Yuan H R, Liu T, Zhu T X, Liu Y, Li X, Chen Y, Duan C X 2023 Acta Phys. Sin. 72 063301
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[18] Liu Y, Li X, Qing T, Duan C X 2025 J. Phys. Chem. A 129 2259
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[19] Gordon I E, Rothman L S, Hargreaves R J, et al. 2022 J. Quant. Spectrosc. Radiat. Transfer 277 107949
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[20] Western C M 2017 J. Quant. Spectrosc. Radiat. Transfer. 186 221
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[21] Suas-David N, Kulkarni V, Benidar A, Kassi S, Georges R 2016 Chem. Phys. Lett. 659 209
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图 1 SF6/Ar/He混合气体在32SF6单体v3带附近的超声射流吸收光谱, 图中标(*), (⊥)和(//)的谱峰分别是32SF6单体v3带、32SF6-Ar复合物的垂直谱带和平行谱带的带心对应的频率位置
Fig. 1. The absorption spectrum of supersonic jet with SF6/Ar/He gas mixtures at the v3 band region of 32SF6, the approximate band-origin position is marked with (*) for the v3 band of 32SF6 monomer, (⊥) for the perpendicular band, and (//) for the parallel band of 32SF6-Ar complex, respectively.
图 2 32SF6单体和32SF6-Ar复合物的吸收光谱 (a) 实验测量光谱; (b) 32SF6-Ar复合物平行和垂直谱带的模拟光谱; (c) 32SF6单体的模拟光谱(考虑多普勒分裂); (d) 32SF6单体的模拟光谱(不考虑多普勒分裂)
Fig. 2. The absorption spectrum of 32SF6 monomer and 32SF6-Ar complex: (a) Observed spectrum; (b) simulated spectrum of the parallel and perpendicular bands of 32SF6-Ar; (c) simulated spectrum of 32SF6 monomer with Doppler splitting; (d) simulated spectrum of 32SF6 monomer without Doppler splitting.
图 3 32SF6单体v3基频带头附近的吸收光谱 (a) 实验测量光谱, 为了放大显示复合物的谱线, 单体的吸收谱线上部已被截断; (b) 32SF6-34SF6的模拟光谱, 线宽0.005 cm–1, 转动温度 3 K
Fig. 3. An expanded view of the absorption spectrum close to the v3 band-origin of 32SF6: (a) Observed spectrum, the absorption lines of the monomer are truncated in order to view the lines of the complex; (b) simulated spectrum of 32SF6-34SF6, assuming a linewidth of 0.005 cm–1 and a rotational temperature of 3 K.
表 1 32SF6-Ar复合物的分子参数 (单位: cm–1)a
Table 1. Molecular parameters of 32SF6-Ar complex (in cm–1)a.
参数 Ref. [15] This work 基态 A" 0.0874b 0.0874b B'' 0.022765(45) 0.022739(39) 平行谱带 v0 946.97950(48) 946.97987(46) A' 0.086804(85) 0.08726(11) B' 0.020733(36) 0.020739(31) 垂直谱带 v0 947.392c 947.45300(58) A' — 0.08844(12) B' — 0.023750(57) ξ — 0.6974(19) q — –0.002325(70) 注: a 括号中的数字为标准偏差, 与参数值的最后两位对齐; b 固定于从头计算得到的值; c RQ(J, 0)支的峰值位置. 表 2 32SF6-Ar复合物的谱线频率 (单位: cm–1)
Table 2. Spectral line frequency of 32SF6-Ar complex (in cm–1).
J' K' J'' K'' Obs. freq. Cal. freq. vobs–vcal 5 0 6 0 946.6470 946.6470 0 4 0 5 0 946.7109 946.7125 –0.0016 3 0 4 0 946.7724 946.7740 –0.0016 2 0 3 0 946.8324 946.8314 0.0010 2 1 3 1 946.8326 946.8333 –0.0007 2 2 3 2 946.8393 946.8389 0.0005 1 0 2 0 946.8879 946.8849 0.0030 1 1 2 1 946.8882 946.8868 0.0015 3 3 3 3 946.9726 946.9726 0 2 2 2 2 946.9785 946.9753 0.0032 1 0 0 0 947.0217 947.0213 0.0004 2 0 1 0 947.0586 947.0588 –0.0003 2 1 1 1 947.0598 947.0607 –0.0009 3 0 2 0 947.0914 947.0923 –0.0009 3 1 2 1 947.0932 947.0942 –0.0010 4 0 3 0 947.1204 947.1218 –0.0014 4 1 3 1 947.1220 947.1236 –0.0017 4 2 3 2 947.1283 947.1292 –0.0009 4 3 3 3 947.1364 947.1385 –0.0021 5 0 4 0 947.1476 947.1473 0.0003 5 1 4 1 947.1479 947.1491 –0.0012 5 2 4 2 947.1557 947.1547 0.0010 6 0 5 0 947.1709 947.1687 0.0021 6 2 5 2 947.1768 947.1762 0.0006 7 0 6 0 947.1846 947.1862 –0.0016 7 2 6 2 947.1949 947.1936 0.0012 8 0 7 0 947.2007 947.1997 0.0010 3 1 4 2 947.2095 947.2096 –0.0001 3 1 4 0 947.2375 947.2385 –0.0010 2 1 3 2 947.2528 947.2520 0.0008 2 1 3 0 947.2719 947.2710 0.0010 1 1 2 2 947.2935 947.2935 0 1 1 2 0 947.3059 947.3077 –0.0019 3 1 3 0 947.3920 947.3925 –0.0005 4 0 4 1 947.3920 947.3917 0.0003 3 3 3 2 947.4224 947.4216 0.0007 4 3 4 2 947.4366 947.4367 –0.0001 1 1 0 0 947.4441 947.4442 0 2 1 1 0 947.5001 947.4983 0.0018 2 2 1 1 947.5002 947.4997 0.0005 3 3 2 2 947.5575 947.5581 –0.0006 3 1 2 0 947.5578 947.5569 0.0009 4 4 3 3 947.6189 947.6186 0.0003 4 1 3 0 947.6197 947.6197 0 5 4 4 3 947.6821 947.6825 –0.0004 5 3 4 2 947.6843 947.6846 –0.0004 表 3 SF6二聚体的分子参数 (单位: cm–1)a
Table 3. Molecular parameters of SF6 dimer (in cm–1)a.
Parameter (32SF6)2b 32SF6-34SF6 A'' 0.04554(6) 0.04554c B'' 0.0083811(26) 0.0083811c $ {\nu }_{0}^{\perp } $ 956.09502(37) 948.1181(12) A' 0.04551(fixed) 0.04551c B' 0.0083803(28) 0.0083803c ξ (unitless) 0.66796(70) 0.66796c 注: a 括号中的数字为标准偏差, 与参数值的最后两位对齐; b 文献[9]; c 固定于(32SF6)2对应参数的值. 表 4 32SF6-34SF6复合物的谱线频率 (单位: cm–1)
Table 4. Spectral line frequency of 32SF6-34SF6 complex (in cm–1).
J' K' J'' K'' Obs. freq. Cal. freq. vobs-vcal 3 2 4 3 947.9943 947.9876 0.0068 2 2 3 3 948.0101 948.0043 0.0058 4 1 5 0 948.0178 948.0110 0.0068 12 3 12 4 948.0422 948.0412 0.0010 11 2 11 3 948.0574 948.0545 0.0029 11 1 11 2 948.0665 948.0678 –0.0013 11 0 11 1 948.0803 948.0812 –0.0010 11 2 11 1 948.1048 948.1082 –0.0034 11 3 11 2 948.1132 948.1218 –0.0086 12 4 12 3 948.1283 948.1354 –0.0071 5 1 4 0 948.1766 948.1786 –0.0020 -
[1] Makarov G N 2005 Phys. -Usp. 48 37
Google Scholar
[2] Zellweger J M, Philippoz J M, Melinon P, Monot, van den Bergh H 1984 Phys. Rev. Lett. 52 522
Google Scholar
[3] Eerkens J W 1998 Laser Part. Beams 16 295
Google Scholar
[4] Makarov G N 2015 Phys. -Usp. 58 670
Google Scholar
[5] 李业军, 郭静, 马俊平, 唐显, 李鑫, 闫冰 2022 物理学报 71 243401
Google Scholar
Li Y G, Guo J, Ma J P, Tang X, Li X, Yan B 2022 Acta Phys. Sin. 71 243401
Google Scholar
[6] Geraedts J, Setiadi S, Stolte S, Reuss J 1981 Chem. Phys. Lett. 78 277
Google Scholar
[7] Geraedts J, Stolte S, Reuss J 1982 Zeit. Phys. A 304 167
Google Scholar
[8] Urban R D, Takami M 1995 J. Chem. Phys. 103 9132
Google Scholar
[9] Asselin P, Potapov A, Turner A C, Boudon V, Bruel L, Gaveau M A, Mons M 2017 Phy. Chem. Chem. Phys. 19 17224
Google Scholar
[10] Kolomiitsova T D, Mielke Z, Shchepkin D N, Tokhadze K G 2002 Chem. Phys. Lett. 357 181
Google Scholar
[11] Tokhadze I K, Kolomiitsova T D, Shchepkin D N, Tokhadze K G, Mielke Z 2009 J. Phys. Chem. A 113 6334
Google Scholar
[12] van Bladel J W I, van der Avoird A 1990 J. Chem. Phys. 92 2837
Google Scholar
[13] Vazhappilly T, Marjolin A, Jordan K J 2016 J. Phys. Chem. B 120 1788
Google Scholar
[14] Hartmann M, Miller R E, Toennies J P, Vilesov A F 1996 Science 272 1631
Google Scholar
[15] Asselin P, Turner A C, Bruel L, Brenner V, Gaveau M A, Mons M 2018 Phy. Chem. Chem. Phys. 20 28105
Google Scholar
[16] Luo W, Zhang Y L, Li W G, Duan C X 2017 J. Mol. Spectrosc. 334 22
Google Scholar
[17] 袁洪瑞, 刘涛, 朱天鑫, 刘云, 李响, 陈杨, 段传喜 2023 物理学报 72 063301
Google Scholar
Yuan H R, Liu T, Zhu T X, Liu Y, Li X, Chen Y, Duan C X 2023 Acta Phys. Sin. 72 063301
Google Scholar
[18] Liu Y, Li X, Qing T, Duan C X 2025 J. Phys. Chem. A 129 2259
Google Scholar
[19] Gordon I E, Rothman L S, Hargreaves R J, et al. 2022 J. Quant. Spectrosc. Radiat. Transfer 277 107949
Google Scholar
[20] Western C M 2017 J. Quant. Spectrosc. Radiat. Transfer. 186 221
Google Scholar
[21] Suas-David N, Kulkarni V, Benidar A, Kassi S, Georges R 2016 Chem. Phys. Lett. 659 209
Google Scholar
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