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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

High-resolution nonlinear laser wave-mixing spectroscopy for gas-phase environmental and atmospheric studies /

Briggs, Ronald D. January 2004 (has links)
Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 2004. / Vita. Includes bibliographical references (leaves 192-200).

Laser Raman spectroscopy of adsorbed species pyridine and n-butenes on silica gel /

Schrader, Glenn LaRue, January 1976 (has links)
Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 170-175).

Four-wave mixing spectroscopy of organic systems

Nguyẽ̂n, Đình Công. January 1984 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographies.

Laser spectroscopy of transition metal nitrides

江河, Jiang, He. January 1999 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

Laser spectroscopy of iridium compounds

Pang, Hon-fung., 彭漢鋒. January 2009 (has links)
published_or_final_version / Chemistry / Master / Master of Philosophy

High sensitivity collinear spectroscopy on strontium isotopes

Fawcett, M. J. January 1988 (has links)
No description available.

Collisional and radiative processes in atomic spectra

Hedley, John January 1995 (has links)
No description available.

Ionisation studies on some small molecules

Peng, Wei-Xian January 1997 (has links)
No description available.

High resolution infrared laser spectroscopy in the solid and gas phases.

January 2015 (has links)
本論文旨在利用高分辨激光光譜研究中紅外以及近紅外波段的分子體系。首先在固態氫體系中,我們主要研究其分別位於4 μm 及1.5 μm 的純轉動和振動轉動的W 躍遷(ΔJ=6)。我們搭建了一套全新的差頻激光光譜儀用以研究純轉動的W1(0)躍遷(ΔJ=6);另外振動轉動W₀(0)躍遷(Δv=1,ΔJ=6)則是用到自行搭建的近紅外二極管激光光譜儀。由於激光光譜的分辨率極高,兩種W 躍遷都觀察到晶體場效應導致的三重分裂結構,我們基於定態激子模型還得到了相應的晶體場常數。另外,我們還研究了兩種W 躍遷的線型、頻率與溫度的關係(溫度在3.8 K 至11.8 K 區間),并基於德拜兩能級弛豫模型對此做出解釋,相信主要是由於晶體內聲子散射所引致的。 / 另外我們還研究了三種含過渡金屬元素的氣態雙原子分子,分別是RuC、IrP和IrB。通過聯用激光消融及超聲射流技術,我們研究這些分子體系在近紅外波段的激光誘導熒光光譜。對於RuC 分子,我們記錄了12000 至14000 cm⁻¹ 波段的電子光譜,包擴[附圖]和[附圖]這四個譜帶系統,并分析得到了所有七種同位素分子的各項分子常數。由於極高的分辨率,我們觀察到99RuC 和101RuC 這兩個同位素分子的超精細結構,并得到了它們的[附圖] 這三個電子態的超精細常數。對於IrP 分子,我們在12000 至14000 cm⁻¹ 波段發現了新的電子態躍遷,并得到¹⁹³IrP 和¹⁹¹IrP 這兩種同位素分子的分子常數。對於IrB 分子,我們指認了一個新的電子態躍遷³Δ₃-X³Δ₃,并得到了¹⁹¹Ir¹¹B and ¹⁹³Ir¹¹B 這兩種同位素分子的分子常數。 / This thesis reports the high resolution laser spectroscopic studies of molecular systems in the mid‐ and near‐ infrared regions. In the system of solid parahydrogen, spectrum in the pure rotational and rovibrational W (ΔJ=6) transitions in the 4 μm and 1.5 μm regions respectively have been studied. A high resolution difference frequency laser spectrometer was constructed from scratch for the study of the pure rotational W₀(0) (ΔJ=6) transition, while the rovibrational W₁(0) (Δv=1, ΔJ=6) transition was studied using a home‐built near infrared diode laser spectrometer. The exceedingly high resolution achieved by laser spectroscopy resolved the triplet structure for both transitions due to anisotropic crystal field interactions. Their corresponding crystal field parameters based on the model of localized exciton were determined. In addition, the temperature dependences of line profiles and transition frequencies in the range of 3.8‐11.8 K were also studied for both transitions. These observations were consistent with the Debye’s model for the dephasing of two‐level system by acoustic phonons in the bulk crystal. / Coupled with laser ablation and free jet expansion, high resolution laser induced fluorescence spectroscopy in the near infrared region was applied in the study of three transition metal containing diatomic molecules including RuC, IrP and IrB in the gas phase. For RuC molecule, rotational resolved electronic spectrum have been observed in the range of 12000‐14060 cm⁻¹, covering the [with formula], and the [with formula] band systems. The resolution of our spectrum allowed partially resolved hyperfine structure for both ⁹⁹RuC and ¹°¹RuC isotopes. Accurate molecular constants for all seven RuC isotopic molecules were obtained and hyperfine constants for the [with formula] and states of both ⁹⁹RuC and ¹°¹RuC isotopes were retrieved and analyzed. For IrP molecule, new electronic transition systems were observed in the range of 12000‐14000 cm⁻¹ and the molecular constants for both ¹⁹³IrP and ¹⁹¹IrP isotopes were obtained. For IrB molecule, a new ³Δ₃-X³Δ₃ transition system was identified with the molecular constants of two isotopes ¹⁹¹Ir¹¹B and ¹⁹¹Ir¹¹B derived. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Yang, Mei. / Thesis (Ph.D.) Chinese University of Hong Kong, 2015. / Includes bibliographical references (leaves 82-85). / Abstracts also in Chinese.

Conversion of laser phase noise to amplitude noise in a Lummer-Gehrcke interferometer and in oxygen gas

Wichner, Brian D. 16 June 1998 (has links)
In order to observe laser phase noise, this noise must be converted to amplitude noise, which can be achieved using either an interferometer or an absorption resonance in an atomic/molecular vapor or gas. When phase noise is converted to amplitude noise, it is manifested as a heterodyne signal in the output of an optical square-law detector. Thus, phase noise is measured by optical heterodyne spectroscopy, or, equivalently, laser phase noise spectroscopy. In recent work on diode laser noise spectroscopy of rubidium and oxygen, the observed spectroscopic lineshapes were not in total agreement with theoretical predictions. We have repeated the previous work on the oxygen A-band transitions, and we now find qualitative agreement with theory. In addition, we have measured the diode laser noise spectrum of a Lummer- Gehrcke interferometer (LGI), comparing the heterodyne lineshape of a LGI transmission spectrum with a qualitative theory that we develop in this thesis. A theory, from other workers, predicts the intensity fluctuations from a Doppler-broadened, two-level atomic/molecular system driven with a phase-diffusing laser field. We show that a simplified version of this theory, which ignores Doppler effects of the system, is a useful approximation to the complete theory, by comparing computer-generated heterodyne lineshapes of each, for a rubidium transition. We apply this approximate theory to an oxygen A-band transition, and compare these results with our experimental measurements. For the experimental arrangement used in the present work, diode laser noise spectroscopy may also include effects of selective reflection, which is dealt with experimentally and theoretically. Diode laser phase noise has practical importance in optical communications and atomic clocks. / Graduation date: 1999

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