H.H. Teo

High-resolution FTIR spectroscopy of the v11 and v2 + v7 bands of ethylene-d4

The Fourier transform infrared spectrum of the v11 band of ethylene-d4 (C2D4) has been recorded with an unapodized resolution of 0.006 cm−1 in the frequency range 2150 to 2250cm−1. The v11 band, with a band centre of about 2201 cm−1, was found to be perturbed by the nearby v2 + v7 band centred at about 2235 cm−1 by a b-type Coriolis interaction. By fitting a total of 772 infrared transitions of v11 using a Watsons A-reduced Hamiltonian in the Ir representation with the inclusion of b-type Coriolis interaction term, two sets of constants, up to quartic distortion constants for the v11 = 1 state, and principal rotational constants for the v2 + v7 = 1 dark state, were derived. The inertia defect of the v11 state was found to be 0.0693 ± 0.0004u Å2.

High-resolution Fourier transform infrared spectroscopy and analysis of the ν12 fundamental band of ethylene-d4

Abstract The Fourier transform infrared (IR) spectrum of the ν 12 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 1030–1130 cm −1 . A total of 1340 assigned transitions have been analyzed and fitted using a Watsons A-reduced Hamiltonian in the I r representation to derive rovibrational constants for the upper state ( v 12 =1) up to five quartic terms with a standard deviation of 0.00042 cm −1 . They represent the most accurate constants for the band thus far. The ground state rovibrational constants were also further improved by a fit of combination–differences from the IR measurements. The relatively unperturbed band was found to be basically A-type with a band centre at 1076.98492±0.00003 cm −1 .

Analysis of the coriolis interaction of the ν12 band with 2ν10 of cis-d2-ethylene by high-resolution Fourier transform infrared spectroscopy

Abstract The Fourier transform infrared spectrum of the ν 12 band of cis-d 2 -ethylene ( cis -C 2 H 2 D 2 ) has been recorded with an unapodized resolution of 0.0024 cm −1 in the frequency range of 1280–1400 cm −1 . This band was found to be mutually coupled by Coriolis interaction with the unobserved 2 ν 10 band situated approximately 10 cm −1 below ν 12 . By fitting a total of 771 infrared transitions of ν 12 with a standard deviation of 0.00075 cm −1 using the Watsons Hamiltonian with the inclusion of a c -type Coriolis resonance term, a set of accurate rovibrational constants for V 12 =1 state was derived. The ν 12 band is A type with a band centre at 1341.1512±0.0001 cm −1 . Accurate rovibrational constants for the V 10 =2 state were also derived.

High resolution FTIR spectrum of the ν6 band of deuterated formic acid (DCOOH)

Abstract The high resolution FTIR spectrum of the ν 6 band of DCOOH has been measured with a resolution of 0.004 cm −1 in the spectral range of 920–1020 cm −1 . The ν 6 band was found to be perturbed by the neighbouring ν 8 band situated at about 100 cm −1 lower. Using a Watson’s A -reduced Hamiltonian in the I r representation, and with the inclusion of a -, and b -Coriolis coupling constants, a simultaneous fit of ν 6 and ν 8 was performed, fitting a total of 1656 infrared transitions of ν 6 with an rms uncertainty of 0.00038 cm −1 . A set of accurate rovibrational constants for ν 6 were obtained. The ν 6 band was analysed to be primarily A -typed with a band centre at 970.88931±0.00003 cm −1 .

High resolution FTIR spectrum of the ν1 band of DCOOD

Accurate spectral information on formic acid has wide application to radioastronomy since it was the first organic acid found in interstellar space. In this work, the infrared absorption spectrum of the nu1 band of deuterated formic acid (DCOOD) has been measured on a Bomem DA3.002 Fourier transform spectrometer in the wavenumber region 2560-2690 cm(-1) with a resolution of 0.004 cm(-1). A total of 292 infrared transitions have been assigned in this hybrid type A and B band centred at 2631.8736 +/- 0.0004 cm(-1). The assigned transitions have been fitted to give a set of eight rovibrational constants for the nu1 = 1 state with a standard deviation of 0.00078 cm(-1).

High-resolution FTIR spectroscopy of the Coriolis interacting nu3 and nu9 fundamentals of methylene fluoride-d2

The Fourier transform infrared spectrum of the υ 3 and υ 9 bands of methylene fluoride-d 2 (CD2F2) has been recorded with an unapodized resolution of 0.0024cm-1 in the frequency range 970-1080cm-1. These two bands with band centres approximately 26 cm-1 apart were mutually coupled by Coriolis interactions. By fitting a total of 1639 infrared transitions of both υ 3 and υ 9 with a standard deviation of 0.00084cm-1 S/S using a Watsons A-reduced Hamiltonian in the I r representation with the inclusion of a first order c-type Coriolis resonance term, two sets of rovibrational constants for υ 3 = 1 and υ 9 = 1 states were derived. The υ 3 band is B-type while the υ9 band is A-type with band centres at 1030.1573 ± 0.0003 and 1003.7435 ± 0.0001cm-1, respectively.

High-resolution FTIR spectroscopy of the ν6 fundamental of methylene fluoride-d2

Abstract The Fourier transform infrared (IR) spectrum of the ν6 band of methylene fluoride-d2 (CD2F2) has been recorded with an unapodized resolution of 0.006 cm−1 in the frequency range 2220–2340 cm−1. A total of 1111 IR transitions of ν6 were used with Watsons A- and S-reduced Hamiltonians in the Ir representation to derive rovibrational constants for the upper state (ν6=1) up to four quartic terms. This relatively unperturbed band was found to be of C-type with an unperturbed band centre at 2283.73996±0.00007 cm−1.