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Rovibrational analyses of formaldehyde, formic acid, and ethylene isotopologues by high-resolution Fourier transform infrared (FTIR) spectroscopy
Author
Rabia'tul A'dawiah Mohamed Yazid
Supervisor
Tan, Augustine Tuck Lee
Abstract
This thesis describes the details of the work done on the experiments and analyses of the formaldehyde, formic acid, and ethylene molecules. Rovibrational analyses of:
1) 2π2 overtone bands of formaldehyde (H212CO) and its isotopologues (H213CO and D212CO);
2) π2 fundamental bands of formic acid isotopologues (H12COOD and H13COOD); and,
3) for ethylene isotopologues, the π7+π8 band of 12C2D4, π9, π11 and π7+π8 bands of 13C2D4 were carried out.
The Bruker IFS 125 HR Fourier transform infrared spectrometer was used in the collection of all spectra at unapodized resolutions of 0.0063 cm-1 or 0.0019 cm-1. All the analyses done in this thesis were carried out using the Watsonβs A-reduced Hamiltonian in the I r representation.
The Fourier transform infrared (FTIR) absorption spectra of the A-type 2π2 overtone bands of formaldehyde H212CO and its isotopologue H213CO were recorded at an unapodized resolution of 0.0063 cm-1 in the 3300-3540 cm-1 region. Analysis of new transitions for H212CO measured in this work yielded upper state constants with greater accuracy than previously reported. The infrared transitions of the 2π2 band of H213CO were measured for the first time.
A low-resolution (0.5 cm-1) Fourier transform infrared (FTIR) spectrum of formaldehyde-d2 (D212CO) in the 2500-4500 cm-1 region was recorded to study the vibrational bands in this region. Several combination and overtone bands were identified, and their band centres and types were determined. The high-resolution (0.0063 cm-1) FTIR spectrum of the A-type 2π2 band of D212CO was recorded and its infrared lines were analysed for the first time.
In the rovibrational analysis of the predominantly B-type, A/B-hybrid π2 band of H12COOD, the π£2=1 state was found to be coupled with the (π£7=3,π£8=1) state by a- and b-Coriolis interactions. Unperturbed and perturbed transitions of the π2 band were analyzed to obtain the a- and b-Coriolis resonance parameters from its interaction with the 3π7+π8 band. The rotational constant B and the band centre of the 3π7+π8 band (which is too weak for detection) were derived for the first time in this work. The rovibrational parameters along with the band centre of the π2 band of H12COOD were also determined for the first time in this work.
The rovibrational analysis of the A/B-hybrid π2 band of H13COOD yielded new rovibrational constants and band centre of the π£2=1 state of H13COOD. The band was found to be primarily B-type with a- and b-Coriolis resonance interactions with the 3π7+π8 band. The rotational constants A and B along with the band centre of the 3π7+π8 band were also derived for the first time in this work. Additionally, the ground state rovibrational parameters of the H13COOD molecule were determined with higher precision than previous work using the ground state combination-differences (GSCDs) method. All the rotational constants determined for the π£2=1,(π£7=3,π£8=1) and ground state were in close agreement with theoretically calculated values using B3LYP and MP2 levels with the cc-pVTZ and cc-pVQZ basis sets.
The FTIR spectrum of deuterated ethylene (12C2D4) in the 1443-1550 cm-1 region was recorded at an unapodized resolution of 0.0063 cm-1 to analyze its A-type π7+π8 band. The majority of the rotational energy levels of the (π£7=π£8=1) state of 12C2D4 were perturbed by the nearby (π£4=π£8=1) state by a c-type Coriolis interaction. Rovibrational analysis of the IR transitions (both perturbed and unperturbed) of the π7+π8 band allows for the c-type Coriolis resonance parameters for the π7+π8 and π4+π8 interacting bands to be determined for the first time. In addition, the band centre and three rotational constants (A, B and C) of the unobserved π4+π8 band were also derived from the perturbed analysis of this work. The rotational constants of the π7+π8 and π4+π8 bands derived from this study were found to agree with the calculated values using MP2/cc-pVQZ and B3LYP/cc-pVQZ levels of theory.
Rovibrational analyses were done on the π9,π11 and π7+π8 bands of 13C2D4 using a FTIR spectrum of a resolution of 0.0019 cm-1. In addition, the combination bands that lie in the 2000-4800 cm-1 region: π2+π12, π6+π11, π6+π9, π1+π12, π5+π12, π2+π11, π2+π9, π5+π11 and π5+π9 were identified, and their band centres (with an uncertainty of Β± 0.1 cm-1) and band types were determined. The fundamental π9 and π11 bands were reanalysed with improved precision. Additionally, the ground state rovibrational constants of 13C2D4 were improved during the analyses. The A-type π7+π8 band was analysed for the first time. Some of the transitions of the π7+π8 band were perturbed by the upper energy levels of the π4+π8 band by a c-type Coriolis interaction. Rovibrational analysis of the perturbed and unperturbed infrared transitions of the π7+π8 band allows for the c-type Coriolis resonance parameters to be determined for the first time. The rotational constants of both π£7=π£8=1 and π£4=π£8=1 states derived from this work were found to be in excellent agreement with the calculated values using MP2/cc-pVQZ and B3LYP/cc-pVQZ levels of theory.
1) 2π2 overtone bands of formaldehyde (H212CO) and its isotopologues (H213CO and D212CO);
2) π2 fundamental bands of formic acid isotopologues (H12COOD and H13COOD); and,
3) for ethylene isotopologues, the π7+π8 band of 12C2D4, π9, π11 and π7+π8 bands of 13C2D4 were carried out.
The Bruker IFS 125 HR Fourier transform infrared spectrometer was used in the collection of all spectra at unapodized resolutions of 0.0063 cm-1 or 0.0019 cm-1. All the analyses done in this thesis were carried out using the Watsonβs A-reduced Hamiltonian in the I r representation.
The Fourier transform infrared (FTIR) absorption spectra of the A-type 2π2 overtone bands of formaldehyde H212CO and its isotopologue H213CO were recorded at an unapodized resolution of 0.0063 cm-1 in the 3300-3540 cm-1 region. Analysis of new transitions for H212CO measured in this work yielded upper state constants with greater accuracy than previously reported. The infrared transitions of the 2π2 band of H213CO were measured for the first time.
A low-resolution (0.5 cm-1) Fourier transform infrared (FTIR) spectrum of formaldehyde-d2 (D212CO) in the 2500-4500 cm-1 region was recorded to study the vibrational bands in this region. Several combination and overtone bands were identified, and their band centres and types were determined. The high-resolution (0.0063 cm-1) FTIR spectrum of the A-type 2π2 band of D212CO was recorded and its infrared lines were analysed for the first time.
In the rovibrational analysis of the predominantly B-type, A/B-hybrid π2 band of H12COOD, the π£2=1 state was found to be coupled with the (π£7=3,π£8=1) state by a- and b-Coriolis interactions. Unperturbed and perturbed transitions of the π2 band were analyzed to obtain the a- and b-Coriolis resonance parameters from its interaction with the 3π7+π8 band. The rotational constant B and the band centre of the 3π7+π8 band (which is too weak for detection) were derived for the first time in this work. The rovibrational parameters along with the band centre of the π2 band of H12COOD were also determined for the first time in this work.
The rovibrational analysis of the A/B-hybrid π2 band of H13COOD yielded new rovibrational constants and band centre of the π£2=1 state of H13COOD. The band was found to be primarily B-type with a- and b-Coriolis resonance interactions with the 3π7+π8 band. The rotational constants A and B along with the band centre of the 3π7+π8 band were also derived for the first time in this work. Additionally, the ground state rovibrational parameters of the H13COOD molecule were determined with higher precision than previous work using the ground state combination-differences (GSCDs) method. All the rotational constants determined for the π£2=1,(π£7=3,π£8=1) and ground state were in close agreement with theoretically calculated values using B3LYP and MP2 levels with the cc-pVTZ and cc-pVQZ basis sets.
The FTIR spectrum of deuterated ethylene (12C2D4) in the 1443-1550 cm-1 region was recorded at an unapodized resolution of 0.0063 cm-1 to analyze its A-type π7+π8 band. The majority of the rotational energy levels of the (π£7=π£8=1) state of 12C2D4 were perturbed by the nearby (π£4=π£8=1) state by a c-type Coriolis interaction. Rovibrational analysis of the IR transitions (both perturbed and unperturbed) of the π7+π8 band allows for the c-type Coriolis resonance parameters for the π7+π8 and π4+π8 interacting bands to be determined for the first time. In addition, the band centre and three rotational constants (A, B and C) of the unobserved π4+π8 band were also derived from the perturbed analysis of this work. The rotational constants of the π7+π8 and π4+π8 bands derived from this study were found to agree with the calculated values using MP2/cc-pVQZ and B3LYP/cc-pVQZ levels of theory.
Rovibrational analyses were done on the π9,π11 and π7+π8 bands of 13C2D4 using a FTIR spectrum of a resolution of 0.0019 cm-1. In addition, the combination bands that lie in the 2000-4800 cm-1 region: π2+π12, π6+π11, π6+π9, π1+π12, π5+π12, π2+π11, π2+π9, π5+π11 and π5+π9 were identified, and their band centres (with an uncertainty of Β± 0.1 cm-1) and band types were determined. The fundamental π9 and π11 bands were reanalysed with improved precision. Additionally, the ground state rovibrational constants of 13C2D4 were improved during the analyses. The A-type π7+π8 band was analysed for the first time. Some of the transitions of the π7+π8 band were perturbed by the upper energy levels of the π4+π8 band by a c-type Coriolis interaction. Rovibrational analysis of the perturbed and unperturbed infrared transitions of the π7+π8 band allows for the c-type Coriolis resonance parameters to be determined for the first time. The rotational constants of both π£7=π£8=1 and π£4=π£8=1 states derived from this work were found to be in excellent agreement with the calculated values using MP2/cc-pVQZ and B3LYP/cc-pVQZ levels of theory.
Date Issued
2021
Call Number
QD96.I5 Rab
Date Submitted
2021