ABSTRACT
The nu(12) band of trans-d(2)-ethylene (trans-C(2)H(2)D(2)) has been recorded with an unapodized resolution of 0.0024 cm(-1) in the frequency range of 1240-1360 cm(-1) by Fourier transform infrared (FTIR) spectroscopy. This band was found to be relatively free from any local frequency perturbations. By fitting a total of 1185 infrared transitions of nu(12) with a standard deviation of 0.00043 cm(-1) using a Watson's A-reduced Hamiltonian in the I(r) representation, a set of accurate rovibrational constants for v(12) = 1 state was derived. The nu(12) band is A type with a band center at 1298.03797 +/- 0.00004 cm(-1). Copyright 2000 Academic Press.
ABSTRACT
The infrared spectrum of the nu(12) fundamental band of ethylene (C(2)H(4)) has been measured with an unapodized resolution of 0.004 cm(-1) in the frequency range of 1380-1500 cm(-1) using the Fourier transform technique. By assigning and fitting a total of 1387 infrared transitions using a Watson's A-reduced Hamiltonian in the I(r) representation, rovibrational constants for the upper state (v(12) = 1) up to five quartic and three sextic centrifugal distortions terms were derived. They represent the most accurate constants for the band so far. The rms deviation of the fit was 0.00033 cm(-1). The A-type nu(12) band with a band center at 1442.44299 +/- 0.00003 cm(-1) was found to be relatively free from local frequency perturbations. The inertial defect Delta(12) was found to be 0.24201 +/- 0.00002 u Å(2). Copyright 2000 Academic Press.
ABSTRACT
The Fourier transform infrared (FTIR) spectrum of the nu(6) band of formic acid (HCOOH) has been recorded with a resolution of 0.0024 cm(-1) in the spectral range 1050-1160 cm(-1). The nu(6) band was found to be strongly perturbed by the nearby nu(8) band centered at about 1033.5 cm(-1). Using a Watson's A-reduced Hamiltonian in the I(r) representation, and with the inclusion of a-type Coriolis coupling constant, a simultaneous fit of nu(6) and nu(8) was performed. A total of 2485 infrared transitions including about 700 perturbed transitions of nu(6) and 19 transitions of nu(8) was fitted with an rms uncertainty of 0.0006 cm(-1). Accurate rovibrational constants up to sextic order for both nu(6) and nu(8) were obtained. The nu(6) band was analyzed to be a type AB hybrid with a band center at 1104.852109 +/- 0.000050 cm(-1). The band center for nu(8) was found to be 1033.4647 +/- 0.0021 cm(-1). Copyright 2000 Academic Press.
ABSTRACT
The spectrum of the nu(9) fundamental band of ethylene-d(4) (C(2)D(4)) has been measured with an unapodized resolution of 0.004 cm(-1) in the frequency range of 2300-2400 cm(-1) using a Fourier transform infrared spectrometer. A total of 549 transitions have been assigned and fitted using a Watson's A-reduced Hamiltonian in the I(r) representation to derive rovibrational constants for the upper state (v(9) = 1) up to five quartic terms with a standard deviation of 0.00087 cm(-1). They represent the most accurate rovibrational constants for the nu(9) band so far. About 30 transitions of K(a)(') = 0, one transition of nu(9) which were identified to be perturbed possibly by the nearby nu(11) and nu(2) + nu(12) transitions, were not included in the final fit. The nu(9) band of C(2)D(4) was found to be basically B-type with an unperturbed band center at 2341.836 94 +/- 0.000 13 cm(-1). Copyright 2000 Academic Press.
ABSTRACT
The infrared spectrum of the nu(7) and nu(9) bands of methylene fluoride-d(2) (CD(2)F(2)) has been recorded with an unapodized resolution of 0.0024 cm(-1) in the frequency range of 940-1030 cm(-1) using the Fourier transform technique. A weak b-type Coriolis interaction term was found to couple these two vibrational states with band centers about 42 cm(-1) apart. By fitting a total of 1031 infrared transitions of both nu(7) and nu(9) with a standard deviation of 0.0011 cm(-1) using a Watson's A-reduced Hamiltonian in the I(r) representation with the inclusion of a b-type Coriolis resonance term, two sets of rovibrational constants for nu(7) = 1 and nu(9) = 1 states up to sextic order were derived. The nu(7) band is C type, while the nu(9) band is A type with band centers at 961.8958 +/- 0.0005 and 1003.7421 +/- 0.0001 cm(-1), respectively. Copyright 2000 Academic Press.
ABSTRACT
The Fourier transform infrared spectrum of the nu(6) and 2nu(9) bands of deuterated formic acid (HCOOD) was recorded with an apodized resolution of 0.004 cm(-1) in the frequency range of 930-1040 cm(-1). These two bands with band centers 40 cm(-1) apart were mutually coupled by Coriolis and Fermi interactions. By fitting a total of 1076 infrared transitions of both nu(6) and 2nu(9) with a standard deviation of 0.00075 cm(-1) using a Watson's A-reduced Hamiltonian in the I(r) representation with the inclusion of c-type Coriolis and a Fermi-resonance term, two sets of rovibrational constants for v(6) = 1, and v(9) = 2 states were derived for the first time. Both nu(6) and 2nu(9) bands are A type with band centers at 972.8520 +/- 0.0001 and 1011.6766 +/- 0.0001 cm(-1), respectively. Copyright 1999 Academic Press.
ABSTRACT
The infrared absorption spectrum of the nu(2) band of deuterated formic acid (DCOOH) was recorded using a Bomem DA3.002 Fourier transform spectrometer in the wavenumber region 2130-2300 cm(-1) with an apodized resolution of 0.004 cm(-1). A total of 1024 transitions were assigned to this band which is hybrid type A and B, centered at 2219.6896 +/- 0.0002 cm(-1). As expected, the nu(2) band is coupled to 2nu(5) by a c-type Coriolis interaction. Both perturbed and unperturbed transitions were assigned and fitted to give seven rovibrational constants for the nu(2) = 1 state with a standard deviation of 0.00094 cm(-1) using Watson's A-reduced Hamiltonian in the I(r) representation. A c-type Coriolis interaction term between nu(2) and 2nu(5) was derived from the rovibrational analysis. The ratio of the transition moments, ||µ(b)/µ(a) ||, was found to be 1.42 +/- 0.10 for the hybrid band. Copyright 1999 Academic Press.
ABSTRACT
The FTIR spectrum of the nu4 band of deuterated formic acid (DCOOD) has been measured with a resolution of 0.004 cm-1 in the frequency range of 1120 to 1220 cm-1. A total of 1866 assigned transitions have been analyzed and fitted using a Watson's A-reduced Hamiltonian in the Ir representation to derive rovibrational constants for the upper state (v4 = 1) with a standard deviation of 0.00036 cm-1. In the course of the analysis, the constants for the ground state were improved by a simultaneous fit of microwave frequencies and combination differences from the infrared measurements. Due to the relatively unperturbed nature of the band, the constants can be used to accurately calculate the infrared line positions for the whole band. Although the band is a hybrid type A and B, only a-type transitions were strong enough to be observed. The band center is at 1170.79980 +/- 0.00002 cm-1. Copyright 1999 Academic Press.
ABSTRACT
The FTIR spectrum of the nu6 band of H13COOH has been collected at a resolution of 0.004 cm-1 in the frequency range of 1030-1160 cm-1. The nu6 band was analyzed to be an A-B hybrid band and perturbed by the nearby nu8 band through a-, and b-Coriolis coupling terms. Using a Watson's A-reduced Hamiltonian in the Ir representation, with the inclusion of a- and b-Coriolis resonances, a total of 3004 IR transitions of nu6 have been analyzed to provide rovibrational constants for the v6 = 1 state with a standard deviation of 0.00047 cm-1. The nu6 band was found to be centered at 1095.40365 +/- 0.00003 cm-1. Copyright 1999 Academic Press.
ABSTRACT
The high-resolution Fourier transform infrared spectrum of HCOOD has been measured in the nu5 region between 1120 and 1220 cm-1 with a resolution of 0.004 cm-1. As expected for an in-plane vibrational fundamental mode, the nu5 band is a hybrid band consisting of both a-type and b-type transitions. Using the Watson's A-reduced Hamiltonian in the Ir representation, 1943 infrared transitions have been assigned and fitted to give 12 rovibrational constants for the v5 = 1 state. The nu5 band is primarily A type with a band center at 1177.09378 +/- 0.00002 cm-1. It is found that nu5 is slightly perturbed by the nearby 2nu7. About 90 perturbed transitions were identified. Copyright 1998 Academic Press.
ABSTRACT
The Fourier transform infrared spectrum of the nu5 band of deuterated formic acid (DCOOH) has been measured with a resolution of 0.004 cm-1 in the frequency range of 1090-1180 cm-1. Using a Watson's A-reduced Hamiltonian in the Ir representation, a total of 1731 assigned unperturbed transitions have been analyzed to provide rovibrational constants for the upper state (v5 = 1) with a standard deviation of 0.000363 cm-1. The band is A type with an unperturbed band center at 1142.31075 +/- 0.00002 cm-1. The band is expected to be perturbed by a nearby nu4 band through a Fermi resonance term and possibly a Coriolis term. The resonance is particularly noticeable for Ka = 10, and 11, at high J values. About 215 perturbed lines were identified but they were not included in the final fit. Copyright 1998 Academic Press.
ABSTRACT
The high-resolution FTIR spectrum of the nu8 + nu9 band of HNO3 around 1205 cm-1 has been measured and analyzed. The bright state was found to be strongly perturbed by its neighboring dark state nu6 + nu7 at the coincident levels. Taking account of the DeltaK = ±2 anharmonic resonance, a simultaneous fit of nu8 + nu9 and nu6 + nu7 was performed leading to a good reproduction of the nu8 + nu9 band with a rms uncertainty of 0.00046 cm-1 . A set of rovibrational constants for nu8 + nu9 were accurately determined, while for nu6 + nu7 the rotational constant B and the band origin were obtained.
