Ten gaseous transient metal-containing molecules have been synthesized and studied by high resolution spectroscopy. Transient molecules are molecules with a short lifetime, and they play an important role in chemistry because they are reaction intermediates. One of the difficulties faced in studying transient molecules is their typically low concentrations under laboratory conditions. Three types of sources were used to generate these molecules: 1) an emission source that combines a high temperature furnace with an electrical discharge was used to generate SbH, SbD, TeH, TeD, CdH2, CdD2, HZnCl and BeF2; 2) a King furnace (carbon tube furnace) was used to synthesize CoS; 3) a Broida-type oven (metal flow reactor) was used to generate SrOD. Two spectroscopic techniques were employed to study these molecules: 1) Fourier transform infrared emission spectroscopy was used to study SbH, SbD, TeH, TeD, CdH2, CdD2, HZnCl, BeF2, and CoS. 2) Laser-induced fluorescence spectroscopy was employed to study SrOD. One or two lasers were used to excite the SrOD molecules from the ground state to excited electronic states and then these SrOD molecules relaxed back to the ground state by emitting fluorescence, which was detected by a photomultiplier tube. Significantly-improved spectroscopic constants have been obtained for SbH, SbD, TeH and TeD. For SbH and SbD, the infrared X 3– vibration-rotation bands and the near infrared b 1+ – X 3– transition were observed and rotationally analyzed, and a Hund’s case (a) fit was performed for each of the four observed SbH isotopologues. For TeH and TeD, the X 23/2 vibration-rotation bands and the near infrared X 21/2– X 23/2 transition have been observed and rotationally analyzed, and Hund’s case (a) and case (c) fits were performed for each of the ten observed TeH isotopologues. New spectroscopic constants were obtained for HZnCl, CdH2 and CdD2. These three molecules have been successfully generated in the gas phase for the first time. The fundamental band and one hot band were obtained for the H–Zn stretching mode (1) and for the antisymmetric stretching mode (3) of CdH2 and CdD2. A least-squares fit was performed for each of the four observed HZnCl isotopologues and the twelve observed CdH2 isotopologues For the first time, a complete set of molecular constants for all three vibrational frequencies was experimentally determined for BeF2. Thirteen new hot bands were rotationally analyzed and the 1, 2, and3 vibrational frequencies were directly determined by fitting nineteen bands together. The traditional equilibrium vibrational and rotational constants were obtained for BeF2 by simultaneously fitting the observed vibrational term values and B rotational constants. New spectroscopic constants were obtained for two electronic states of CoS and SrOD, respectively. The A 4i – X 4i and B 4i – X 4i transitions of CoS and the and transitions of SrOD were observed for the first time. Hund’s case (c) fits were performed for the CoS transitions and Hund’s case (a) fits were performed for the SrOD transitions.

Ten gaseous transient metal-containing molecules have been synthesized and studied by high resolution spectroscopy. Transient molecules are molecules with a short lifetime, and they play an important role in chemistry because they are reaction intermediates. One of the difficulties faced in studying transient molecules is their typically low concentrations under laboratory conditions. Three types of sources were used to generate these molecules: 1) an emission source that combines a high temperature furnace with an electrical discharge was used to generate SbH, SbD, TeH, TeD, CdH2, CdD2, HZnCl and BeF2; 2) a King furnace (carbon tube furnace) was used to synthesize CoS; 3) a Broida-type oven (metal flow reactor) was used to generate SrOD. Two spectroscopic techniques were employed to study these molecules: 1) Fourier transform infrared emission spectroscopy was used to study SbH, SbD, TeH, TeD, CdH2, CdD2, HZnCl, BeF2, and CoS. 2) Laser-induced fluorescence spectroscopy was employed to study SrOD. One or two lasers were used to excite the SrOD molecules from the ground state to excited electronic states and then these SrOD molecules relaxed back to the ground state by emitting fluorescence, which was detected by a photomultiplier tube. Significantly-improved spectroscopic constants have been obtained for SbH, SbD, TeH and TeD. For SbH and SbD, the infrared X 3– vibration-rotation bands and the near infrared b 1+ – X 3– transition were observed and rotationally analyzed, and a Hund’s case (a) fit was performed for each of the four observed SbH isotopologues. For TeH and TeD, the X 23/2 vibration-rotation bands and the near infrared X 21/2– X 23/2 transition have been observed and rotationally analyzed, and Hund’s case (a) and case (c) fits were performed for each of the ten observed TeH isotopologues. New spectroscopic constants were obtained for HZnCl, CdH2 and CdD2. These three molecules have been successfully generated in the gas phase for the first time. The fundamental band and one hot band were obtained for the H–Zn stretching mode (1) and for the antisymmetric stretching mode (3) of CdH2 and CdD2. A least-squares fit was performed for each of the four observed HZnCl isotopologues and the twelve observed CdH2 isotopologues For the first time, a complete set of molecular constants for all three vibrational frequencies was experimentally determined for BeF2. Thirteen new hot bands were rotationally analyzed and the 1, 2, and3 vibrational frequencies were directly determined by fitting nineteen bands together. The traditional equilibrium vibrational and rotational constants were obtained for BeF2 by simultaneously fitting the observed vibrational term values and B rotational constants. New spectroscopic constants were obtained for two electronic states of CoS and SrOD, respectively. The A 4i – X 4i and B 4i – X 4i transitions of CoS and the and transitions of SrOD were observed for the first time. Hund’s case (c) fits were performed for the CoS transitions and Hund’s case (a) fits were performed for the SrOD transitions.

abstract: Transient molecules are of great importance having proposed applications in quantum science and technology and tests of fundamental physics. In the present dissertation, the transient molecules studied are SrOH, ThF, ThCl, YbF and YbOH; each having been selected because of their proposed application. Specifically, SrOH is a candidate of constructing a molecular magneto-optical trap (MOT). The simple actinide molecules, ThF and ThCl, were selected as ligand bonding model systems to gain insight into chemical processing of Spent Nuclear Fuel. The lanthanides YbF and YbOH are venues for the determination of electron electric dipole moment (eEDM) and the studies in this dissertation provide the requisite properties for those experiments. Intense supersonic molecular beams of these transient molecules were generated via laser ablation and spectroscopically characterized using a novel medium-resolution two-dimensional (2D) spectroscopic approach, as well as high-resolution laser induced fluorescence (LIF). The 2D medium resolution approach, which was used in the studies SrOH, ThF, ThCl and YbOH, uses a multiplexing method that simultaneously records dispersed fluorescence and excitation spectra. A significant advantage of 2D-LIF imaging is that all the electronics states can be targeted to determine the electronics states and associated vibrational spacing individually. Consequently, in the 2D spectra of ThF, ThCl and YbOH, several previously unobserved band systems have been detected in one single scan. For the DF spectra of SrOH and YbOH, the determined branching ratios show that the transitions of these molecules are diagonal (i.e. Δv=0), which is essential for the proposed potential for laser cooling. In the high-resolution of YbF, ThF, ThCl and SrOH optical spectra were recorded to an accuracy of ±30 MHz, which represents an unprecedented precision of 1:10+8. In addition to field free spectra, optical Stark and Zeeman studies were performed to determine the most fundamental magneto-and electro-static properties. Effective Hamiltonian operators were employed to analyze the recorded spectra and determine the spectroscopic parameters. This data set also establishes a contribution toward developing new computational methodologies for treating relativistic effects and electron correlation. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2019

abstract: This thesis describes the studies for two groups of molecules in the gas-phase: (a) copper monofluoride (CuF) and copper hydroxide (CuOH); (b) thorium monoxide (ThO) and tungsten carbide (WC). Copper-containing molecules (Group a) are selected to investigate the ionic bonding in transition metal-containing molecules because they have a relatively simple electronic state distribution due to the nearly filled 3d-orbital. ThO and WC (Group b) are in support of particle physics for the determination of electron electric dipole moment (eEDM), de, the existence of which indicates new physics beyond the Standard Model. The determination of the tiny eEDM requires large electric fields applied to the electron. The 3(Delta)1 states for heavy polar molecules were proposed [E. R. Meyer, J. L. Bohn, and M. P. Deskevich, Phys. Rev. A 73, 062108 (2006)] to determine de with the following attractive features: (1) large electric dipole moments; (2) large internal electric fields, Eeff, experienced by valence electrons; (3) nearly degenerate omega-doublets; (4) extremely small magnetic dipole moments. The H3(Delta)1 state for ThO and the X3(Delta)1 state for WC are both good candidates. Spectroscopic parameters (i.e. molecular electric and magnetic dipole moments, omega-doubling parameters, etc) are required for the 3(Delta)1 states of ThO and WC. High resolution optical spectra (linewidth ~50 MHz) of CuF, CuOH, ThO and WC were recorded field-free and in the presence of a static electric field (or magnetic field) using laser ablation source/supersonic expansion and laser induced fluorescence (LIF) detection. The spectra were modeled by a zero-field effective Hamiltonian operator and a Stark (or Zeeman) Hamiltonian operator with various molecular parameters. The determined molecular parameters are compared to theoretical predictions. The small omega-doubling parameter was well determined using the pump/probe microwave optical double resonance (PPMODR) technique with a much higher resolution (linewidth ~60 kHz) than optical spectroscopy. In addition to the above mentioned studies of the two groups of molecules, a resonance enhanced multi-photon ionization (REMPI) combined with a time-of-flight mass spectrometer (TOFMS) has been developed to identify the molecules responsible for observed LIF signals. The operation of this spectrometer has been tested by recording the mass spectrum of Ti/O2 and the REMPI spectrum for TiO using a two-color excitation scheme. / Dissertation/Thesis / Ph.D. Chemistry 2012

L'eau joue un rôle fondamental dans la photochimie du milieu interstellaire (MIS), à travers la formation d'espèces très réactives comme OH. Les radicaux OH peuvent par la suite interagir avec d'autres molécules hydrogénées pour reformer H2O par abstraction d'hydrogène: R-H + OH → R* + H2O. Dans le cadre de ce travail de thèse, nous avons étudié l'influence des photons VUV sur des analogues de glace interstellaire. Nous montrons que l'incorporation d'une petite quantité d'eau dans NH3 et CH4 glaces augmente considérablement la formation de radicaux réactifs comme NH2 et CH3 pendant le processus de photolyse et que le chauffage des glaces binaires irradiées telles que NH3-H2O et CH4-H2O conduit à la formation de NH2OH et d'espèces alcooliques plus complexes comme le propanol et le métoxyméthanol. Nous avons également entamé d'autres études en parallèle sur le l'évolution thermique des glaces de NH2OH d'une part et la formation de propanol par voies énergétiques (irradiation VUV) et non énergétique (réaction d'addition H) d'autre part afin de tenter d'expliquer la non-détection des ces espèces organiques dans le milieu interstellaire. L'étude des glaces mixtes irradiées NH3-CH4-H2O a montré la formation à basse température d'espèces plus exotiques en combinant les spectrométries IR et de masse. Nous avons réussi à identifier des composés organiques très complexes déjà détectés ou activement recherchés dans le MIS. / Water plays a fundamental role in the photochemistry of the interstellar medium (ISM), through OH radical formation. OH radicals can interact with other H-containing species to form H2O through a hydrogen abstraction reaction: R-H + OH → R* + H2O. In this work, we have investigated the VUV processing on different interstellar ice analogs. We show that the incorporation of small amount of water in NH3 and CH4 ices greatly increases the formation of reactive NH2 and CH3 radicals during the photolysis processing. Thermal treatments of irradiated NH3-H2O and CH4-H2O ices lead to the formation of NH2OH and larger alcoholic species such as propanol and metoxymethanol. Further studies of thermal processing of NH2OH ice and formation of propanol through energetic (VUV irradiation) and non-energetic (surface H-addition reaction) processing were carried out in the context of this thesis in order to try explaining their non-detection in the interstellar medium. The study of the irradiated mixed NH3-CH4-H2O ices showed the formation of more exotic species by combining the IR and mass spectrometries. We managed to identify very large complex organic compounds already detected or tensively sought in the ISM.