Thesis (M.S.)--Eastern Illinois University, 2009. / Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

This thesis has been written to provide a basic understanding of the spectrometer and to be used as a useful reference for its operation. Discussions of such things as the propagation of microwaves and the mechanics of klystron operations have been avoided.

No description available.

Microwave spectroscopy was used to determine whether sulphonyl chloride isocyanate (SO₂CINCO) exists as a mixture of 71° and 110° isomers or as a single 94° isomer where the angle is the dihedral angle between the S-Cl bond and N = C bond, and whether the NCO group is linear or not. The microwave spectrum of SO₂CINCO was assigned for two isotopic species, SO₂³⁵CINCO and SO₂³⁷CINCO, by considering the Stark effect and the nuclear quadrupole splittings due to chlorine and nitrogen. Rotational constants and nuclear quadrupole coupling constants were determined from the assigned peaks. The bond angles and dihedral angles were derived from the six rotational constants of the two isotopes by imposing some constraints based on the electron diffraction study. The dihedral angle C = N-S-CI obtained in this study was 93.86 ± 0.04 ° and ∠NCO was 175.68 ± 0.02° . The results indicate that SO₂CINCO exists as the 94° form at the temperature (4° K) where the microwave spectrum was recorded and that the NCO group is not linear. / Ph. D.

The microwave spectrum of pentafluorosulfanylisocyanate, SF₅ -N = C = 0 has been investigated in the 8 GHz to 26 GHz region using a conventional Stark modulated spectrometer. Twenty six transitions have been assigned. A rigid rotor fit was performed by using low J transitions. The spectroscopic constants obtained are A = 2707.69 MHz, B = 1191.22 MHz, and C = 1191.13 MHz. These constants are close to those determined by the electron diffraction study on pentafluorosulfanylisocyanate and to this extent tend to support the bent -N = C = 0 structure as proposed by the electron diffraction study. / M.S.

The microwave spectrum of the stable free radical bis-trifluoromethyl nitroxide was analyzed in the 20 to 26.5 GHz region. 39 transitions have been assigned. The rigid rotor rotational constants determined by calculation of the hypothetical unsplit rotational transitions are A= 2256.94 MHz, B= 1056.08 MHz, and C=971.51 MHz. A program to calculate the fine and hyperfine splitting patterns was written which reproduced the experimentally observed splittings. The spin-rotation coupling constants are Eaa = -3597.7 MHz, Ebb= -1121.4 MHz, and Eee = 29.8 MHz. The magnitude of Eee indicates that the unpaired electron is in an orbital extending perpendicularly to the molecular plane. The determined magnetic hyperfme coupling constants are Taa= -183.74 MHz, Tbb= -177.77 MHz, Tee= 361.51 MHz, and aF= 22.8 MHz. The spin density on the fluorine atom is 11.9% which is estimated from the value of Tee· The value of the Fermi coupling constant aF indicates that the unpaired electron occupies an unhybridized p orbital. An insufficient number of unsplit rotational transitions were assigned to allow a centrifugal distortion analysis to be performed. Since isotopic substitution was not feasible an r0 structure was determined by doing a least squares fit of the three moments of inertia. The following parameters were not allowed to vary during the least squares fit: reF= 1.32A,rcN= 1.441A, F - C - F = 109.8° . The calculated structure gave a N-0 bond length of 1.212A ,a C-N-0 angle of 116.9° a C-N-C ·angle of 126.2° , and an angle which measures the deviation of the 0 atom from the CNC plane of 0° . / Ph. D.

The shape of collision-broadened microwave absorption lines is reviewed, along with a number of other broadening mechanisms. The Anderson and Murphy-Boggs linewidth theories are reviewed in detail. Several published modifications to these theories are reviewed. Computer programs which numerically evaluate linewidths and lineshifts are presented. Approximations are made to reduce the need for extensive use of the modified Bessel functions, thereby reducing computation time. Only dipole-dipole forces are considered.

High resolution rotational spectra of ¹⁰BH₃CO, ¹¹BH₃CO, ¹¹BD₃CO, PH₂D and CD₃CN were studied to obtain information concerning the electronic and magnetic properties of these molecules. From the analysis of the hyperfine structure of the rotational spectra of the molecules the following constants were determined: rotational constants (B₀), nuclear quadrupole coupling constants (eOq [x], spin-spin constants D (X-Y) and spin rotation constants (C[x]). The two instruments used in these experiments were a Stark modulated microwave spectrometer and a molecular beam maser spectrometer. The J = 0 to 1, F₁ = 3 to 3 and F₁ = 3 to 4 transitions of ¹⁰BH₃CO were studied. The molecular constants in KHz which were derived from the spectral analysis were: B(,0) = 8980060.3 (+/-) 1.0, eQqₐₐ (¹⁰B) = 3463.- (+/-) 8.0, C(¹⁰B) = .2 (+/-) .2, D(¹⁰B-H) = -2.8 (+/-) .2, D(H-H) = -7.2 (+/-) .5 and C(H) = 0.0 (+/-) .7. All three of the F₁ components of the J = 0 to 1 rotational transition of ¹¹BH₃CO were observed. The molecular constants in KHz which were obtained from the data analysis were: B₀ = 8657333.8 (+/-) .6, eQqₐₐ (¹¹B) = 1661.9 (+/-) 2.3, C(¹¹B) = .7 (+/-) .3, D(¹¹B-H) = 8.3 (+/-) .4, D(H-H) = -6.8 (+/-) .2 and C(H) = .4 (+/-) .4. Only spectra of the J = 0 to 1, F₁ = 3/2 to 3/2 transition of ¹¹BD₃CO were obtained. From the analysis of the spectra the following molecular constants were derived: eQqₐₐ (D) = -48.5 (+/-) 2.3, eQq(,zz)(D) = 116.9 (+/-) 5.4, C(D) = 0.0 (+/-) .8 and D(¹¹B-H) = -1.2 (+OR-) .3. The investigation of the 4₀₄ to 4₁₄ and 1₁₁ to 1₀₁ rotational transitions of PH₂D was unsuccessful in determining any molecular parameters. The spectra of the 4₀₄ to 4₁₄ rotational transition were not amenable to analysis and no spectra were obtained for the 1₁₁ to 1₀₁ rotational transitions. The three components of the J = 0 to 1 rotational transitions of CD₃CN were studied with the maser in the two cavity configuration. The constants in KHz which were determined were: B₀ = 7857978.7 (+/-) .1, eQqₐₐ(N) = -4229.2 (+/-) .6, eQqₐₐ(D) = -55.1 (+/-) .4, eQq(,zz)(D) = 165.5 (+/-) 5.0, C(,N) = 1.7 (+/-) .1 and C(,D) = 0.0 (+/-) .03.

A pulsed-beam fourier transform microwave spectrometer was used to measure the rotational spectra of iodine heptafluoride, iodine pentafluoride, and the weakly bound complex, HCl...NNO. For IF7, only five rotational transitions were observed, and no resolvable hyperfine structure was detected. Based on this data, the A, B, and C rotational constants were determined to be 1746(3) MHz, 1732.0(8) MHz, and 1553.0(2) MHz, respectively. The existence of a pure rotational spectrum confirms that this molecule undergoes polar distortions. Twenty-two hyperfine components of the IF5 spectrum were recorded. The B rotational constant for this molecule was determined to be 2727.421(3) MHz, and the quadrupole coupling constant was found to be 1069.35(13) MHz. Though the work is still in progress on HCl...NNO, nine transitions have been recorded. In addition, five transitions have been recorded for an apparent trimer species composed of HCl, NNO, and an as yet unidentified third species.