High-resolution infrared absorption spectra have been analyzed for two bicyclo[111]pentane isotopologues, C₅H₈ (-d₀) and C₅H₇D (-d₁), where in the latter the D-atom replaces a hydrogen on the C₃ symmetry axis such that the molecular symmetry is reduced from D₃ₕ to C₃ᵥ. Two (a"₂) parallel bands, v₁₇ and v₁₈, of bicyclopentane-d₀...
This paper is a continuation of earlier work in which the high resolution infrared spectrum of [1.1.1]propellane was measured and its k and l structure resolved for the first time. Here we present results from an analysis of more than 16,000 transitions involving three fundamental bands v₁₀ (E' - A'₁),...
The photoelectron spectra of a series of halogenated
molecules have been investigated in the gas phase. Both
core-ionization energies and Auger kinetic energies were
measured to probe the nature of the interaction that holds
a core electron to the molecule.
It was found that satellite structure (shake) could be
used...
A variety of laser spectroscopic methods are employed in this
thesis research for studies of CF₃NO, an interesting model
photodissociative system, and for investigation of low energy rotations
and vibrations of small molecules and low molecular weight clusters in
free jet expansions.
Nonradiative energy decay for electronically excited CF₃NO is...
A high-spectral resolution laser-excited molecular fluorescence
system was developed that utilizes a pulsed supersonic expansion to
simplify the fluorescence excitation spectra of large, gas-phase
aromatic molecules diluted in an excess of a monatomic gas. A
microcomputer was used to control and synchronize the instrumental
components, which included a Chromatix CMX-4...
A new experimental apparatus was built at Oregon State University to perform high resolution stimulated Raman spectroscopy in a pulsed molecular jet at state densities of the order of 10¹¹ cm⁻³. The technique uses a stimulated Raman step to first populate a vibrational/rotational level and then a resonantly enhanced multiphoton...
Two nonlinear optical experiments are presented in which the third-order electronic susceptibility of molecules is used to generate Raman signals. The first one uses a single 532 nm beam from a Nd:YAG laser to produce Stimulated Raman Scattering in benzene and deuterated benzene. With a simple experimental set-up, stimulated emission...
The temporal and spatial characteristics of a laser microprobe plume were investigated using the spectroscopic methods of emission, absorption and fluorescence. The plume was produced by rapid vaporization of a small quantity (1 μg) of a solid sample using a focussed pulsed dye laser (110 MW/cm²). For absorption and fluorescence...
A new x-ray source capable of operating at up to 80
watts has been designed and developed, and put to use with
the Oregon State University Cylindrical Electrostatic
Analyzer. The new source produces over four times the
photoelectron intensity of its predecessor, from gaseous
samples, and accommodates a wider selection...
Plasma sources with multiple electrodes have been developed and
characterized in this research for atomic emission spectroscopy.
Multi-electrode plasma sources use electrodes to shape the plasma in
order to continuously entrain a sample stream in the center of hot
plasma, in a manner similar to an inductively coupled plasma (ICP)...
A nonflame method for atomic absorption spectroscopy is
described. A helical tungsten filament from a commercially available
6-V, 4-A light bulb, heated to :incandescence in an argon atmosphere
is used to atomize 2-μl aqueous samples for metals analyses. Studies
of two hollow cathode lamp tungsten filament orientations, a
modulated light...
Ultrafast spectroscopy can exploit the structure-function relationship of chemical- and biological-based systems. More specifically, femtosecond stimulated Raman spectroscopy (FSRS) provides ground- and excited-state vibrational information with simultaneously high spectral (spatial) and temporal resolutions. The electronic counterpart, femtosecond transient absorption (fs-TA), complements FSRS data analysis as part of a comprehensive approach...
The variable length, six-electrode plasma source for atomic
emission spectroscopy described here is operated from three
compact, simple, and inexpensive direct current power supplies. The
vertical arcs formed between the three electrode pairs completely
entrain the sample and are typically operated at 40 V and 20 A.
Three concentric quartz...
In this dissertation, my research work on excited state dynamics of small organic molecules in solutions is presented. Using femtosecond stimulated Raman spectroscopy (FSRS) as the main experimental tool, the excited state hydrogen-bonding dynamics (ESHBD) of Coumarin 102, a common laser dye molecule, in ethanol solution is examined with <150...
The CARS apparatus at OSU was modified to permit studies in the 0-500 cm⁻¹ spectral region. The new low frequency capabilities were then used to study molecular clusters formed in free expansion jets of carbon dioxide. A strong cluster band was observed at 73 cm⁻¹, with a weaker shoulder at...
The high resolution stimulated Raman spectrometer at OSU was
modified to improve its sensitivity and to extend its range of
applications to low Raman shifts and to the spectroscopy of solids and
liquids. As part of the characterization of the spectrometer, optical
Stark effects on rotational and vibrational transitions of...
The spectrophone method for the study of vibrational relaxation
has been claimed to possess a distinct advantage over the more commonly
used ultrasonic techniques in that it permits the relaxation of
the various infrared-active vibrational modes in a polyatomic molecule
to be studied separately. A discussion of the rate equations...
The techniques of coherent anti-Stokes Raman spectroscopy (CARS)
and inverse Raman spectroscopy (IRS) are used to examine carbon dioxide
aggregation in a supersonic jet expansion. To promote the formation of
small clusters, a BMW injector valve is modified to permit its use as a
pulsed nozzle at very cold temperatures....
In this dissertation, I present electronic spectra of a few polycyclic aromatic hydrocarbons (PAHs): tetracene, pentacene, pyrene, benzo[g,h,i]perylene and benzo[a]pyrene using resonantly enhanced multiphoton ionization (REMPI) and zero kinetic energy (ZEKE) photoelectron spectroscopy. The work of tetracene and pentacene also combine a laser desorption source with a ZEKE spectrometer, demonstrating...
Due to its importance, the phenomenon of hydrogen
bonding has been the subject of much research over the
years. Among the different techniques used to study
hydrogen bonded systems, vibrational spectroscopy is
perhaps the most sensitive because of the striking
changes induced in molecular spectra by the formation of
hydrogen...
Theoretical studies and experimental results are presented for the rotational motion of molecule's in crystalline solids. The group theory is solved for molecules of any symmetry matrix isolated at a site in a crystal field of any symmetry. As the potential terrier to rotation of the molecule relative to the...
The satellite structure ("shake-up") present in the X-ray
photoelectron spectra of several planar molecules containing
double bonds has been investigated in the gas phase.
This set consists of three five-membered heterocyclic
molecules, ethylene and two of its fluorinated analogs, and
benzene with three of its fluorinated analogs. In addition,
core...
The development and applications of a 0.2 cm⁻¹ resolution
Nd-YAG laser powered coherent anti-Stokes Raman
spectroscopy, CARS, spectrometer for gas phase studies is
chronicled in this thesis. Applications including CARS
lineshape analysis, resonant CARS, and CARS of transient
species and excited state molecules is reported.
The intensity of the signal...
The photoelectron spectra of a series of ketone
compounds have been investigated in the gas phase. Core
ionization energies were measured to probe the effects of
molecular size and connectivity number on core ionization
energies.
It was found that core ionization energies roughly
decrease with increasing connectivity number as expected....
In this dissertation, I describe spectroscopic studies of jet-cooled polycyclic aromatic hydrocarbons (PAH) and one nitrogen substituted PAH (PANH) using pulsed field zero kinetic energy (ZEKE) photoelectron spectroscopy and resonantly enhanced multiphoton ionization (REMPI) spectroscopy. Recently, there has been a demand for far-infrared (FIR) spectral information of astrophysically relevant molecules...
The two sulfur isotopomers of sulfur trioxide, ³²S¹⁶O₃ and ³⁴S¹⁶O₃, have been studied via high resolution infrared and Coherent anti-Stokes Raman (CARS) spectroscopy. The v₁ symmetric SO stretching Q-branches observed by the latter are quite different, being especially complex for ³²S¹⁶O₃ Understanding this band structure required analysis of infrared-active hot...
The core-electron ionization potentials for mono- and
di(trifluoromethyl)benzene, for chlorofluoromethanes and for
chlorine have been measured in order to give information on
the electron distribution in these molecules and to investigate
differences between the inductive effect of fluorine
and that of CF3. For trifluoromethylbenzene the measured
ionization potentials in eV...
A procedure for evaluating the precision of atomic absorption
measurements is presented and applied to 21 elements under varying
instrumental conditions. The experimental relative standard deviations
(RSD's) in absorbance obtained from repetitive measurements made
with a high resolution voltmeter and on-line computer, are compared
to those predicted by a recently...
In this dissertation, I present electronic spectroscopy of a few biologically relevant species and their complexes with solvent molecules in the gas phase using a variety of techniques, including resonantly enhanced multiphoton ionization (REMPI), laser induced fluorescence (LIF), and zero kinetic energy (ZEKE) photoelectron spectroscopy. My work on several methylated...
Mapping out multidimensional potential energy surfaces has been a goal of
physical chemistry for decades in the quest to both predict and control chemical
reactivity. Recently a new spectroscopic approach called Femtosecond Stimulated Raman
Spectroscopy or FSRS was introduced that can structurally interrogate multiple
dimensions of a reactive potential energy...
In this thesis, I present a new method we developed to study low frequency (< 700 cm⁻¹) vibrational dynamics: Time-resolved third-harmonic generation (TRTHG) spectroscopy. Among a variety of vibrational spectroscopy techniques, TRTHG differentiates itself with robustness, versatility, and simplicity. In TRTHG experiment, that involves only two ultrashort laser pulses, the...
The physical properties of hydrochloric acid and deuterium chloride were derived through the use of the harmonic oscillator and rigid rotor quantum mechanical models. By first obtaining angular momentum quantum values for HCl and DCl through Fourier Transform Infrared Spectroscopy, these two systems could be summed and processed with additional...
Applications of several methods of coherent nonlinear Raman Spectroscopy have been made in this thesis research. The theory and potential of one of these, Photoacoustic Raman Spectroscopy (PARS), is discussed in chapter two. Experimental results are presented which illustrate the sensitivity of this method and establish sampling conditions for maximum...
The development of a least squares model for the
determination of compliance constants from various combinations
of vibration frequency, mean square amplitudes
of vibration and centrifugal distortion data is discussed.
The resultant model is applied to frequency and mean square
amplitude data for NO₂ and N₂O₄ and to frequency and...
This chapter describes a mass spectrometry-based strategy that facilitates the unambiguous identification and characterization of proteins modified by lipid peroxidation-derived 2-alkenals. The approach employs a biotinylated hydroxyl amine derivative as an aldehyde/keto reactive probe in conjunction with selective enrichment and tandem mass spectrometric analysis. Methodological details are given for model...
We report zero kinetic energy (ZEKE) photoelectron spectroscopy of benzo[a]pyrene (BaP) via resonantly enhanced multiphoton ionization (REMPI). Our analysis concentrates on the vibrational modes of the first excited state (S₁) and those of the ground cationic state (D₀). Similar to pyrene, another peri-condensed polycyclic aromatic hydrocarbon we have investigated, the...
High resolution spectroscopy was used to study the properties of two simple polyatomic molecules, sulfur trioxide, SO₃, and carbon suboxide, C₃O₂. The fundamental modes and several hot bands of the ¹⁸O isotopic fonns of SO₃ (³²S¹⁸O₃ and ³⁴S¹⁸O₃) have been investigated using both infrared spectroscopy and coherent anti-Stokes Raman scattering...
Polyhalogenated benzenes have been analyzed by standard electron capture
chemical ionization mass spectrometry (ECCI/MS), and electron monochromator mass
spectrometer (EM/MS) systems. The EM/MS experiments distinguished electronegative
compounds (especially isomers) by transient negative ions (TNIs) of the same mass but
differing energies and/or the formation of distinct TNIs of different masses...
) .......................................................................................... 40
LIST OF FIGURES (continued)
Figure
Figure 2.11: Virtual molecular orbital eigenvalues (eV
The carbon is photoelectron spectrum of CO₂ has been measured with very high photon energy resolution. The natural lifetime of the carbon is hole state has been determined from a series of spectra taken at photon energies of 308, 320, and 330 eV. The measured values of the lifetimes show...
X-ray photoemission spectroscopy is used in a great variety of research fields; one observable is the sample's stoichiometry. The stoichiometry can be deduced based on the expectation that the ionization cross sections for innershell orbitals are independent of the molecular composition. Here we used chlorine-substituted ethanes in the gas phase...
We use femtosecond stimulated Raman spectroscopy (FSRS) to illuminate the choreography of intermolecular excited-state proton transfer (ESPT) of photoacid pyranine (8-hydroxypyrene-1,3,6-trisulfonic acid, HPTS) in water. The multidimensional reaction coordinate responsible for photoacidity is revealed to involve sequential activation of characteristic skeletal motions during the ca. 1 ps preparation stage preceding...
We report zero kinetic energy (ZEKE) photoelectron spectroscopy via resonantly enhanced multiphoton ionization (REMPI) for benzo[e]pyrene. Extensive vibronic coupling between the first electronically excited state and a nearby state allows b₂ symmetric modes to be observed which would normally be Franck-Condon (FC) disallowed. These vibronic modes are comparable in intensity...
The work presented in this thesis deals with the mechanisms by which a vibrationally excited diatomic molecule gives up its energy to a host monatomic lattice at low temperature. The vibrational lifetimes (v"=1) of the metal oxides Ba0 and A10 in their ground electronic states are studied using pulsed dual...
Femtosecond stimulated Raman spectroscopy (FSRS) is a powerful ultrafast technique which can track photoinduced excited state structural events on femtosecond (fs) to picosecond (ps) timescales. In addition to high temporal and spectral resolutions, FSRS provides a broad spectral window from ca. 100—2000 cm-1 for detection, enabling the direct mapping of...
This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: https://doi.org/10.1016/j.elspec.2012.12.004
The use of gas jets in a sputtering cell makes this direct sampling method practical for atomic absorption and mass spectrometry determinations. With a commercial six-jet sputtering source, the Atomsource (Analyte Corp., Grants Pass, Oregon), that directly atomizes solid samples for conventional atomic absorption spectrophotometers, the sample loss rate for...
The central purpose of this dissertation was to explore and expand the use of
an uniform electric field for orientation and for subsequent spectroscopic investigation of asymmetric polar molecules in the gas phase. The systems of study were nitrobenzene (NB) and the nitrotoluene (NT) isomers. We were able to quantitatively...
In this dissertation, excited state proton transfer (ESPT) and its inhibition in solution and protein environments are revealed using both femtosecond transient absorption (fs-TA) spectroscopy and femtosecond stimulated Raman spectroscopy (FSRS). Using a tunable Raman pump to enhance transient vibrational features of the photoacidic chromophore HPTS in methanol and methanol...
In this dissertation, the spectroscopic properties and thermodynamic stability of a class of materials known as metal oxo and hydroxo clusters are studied. In aqueous solutions, many metals can aggregate into discrete clusters of metals bridged by oxo or hydroxo ligands. These clusters are of particular interest to us for...
In this dissertation, we describe a spectroscopic study of metal clusters and metal-ligand complexes using pulsed field ionization zero kinetic energy (PFI-ZEKE) photoelectron spectroscopy and mass analyzed threshold ionization (MATI) spectroscopy. Vibrational resolved spectra of sodium dimer, Na•NH₃, Na•(NH₃)₂ are presented. These spectra provide a direct measurement of the ionization...
A sensitive technique for the determination of As(III) and As{V)
at μ/L and sub-μg/L concentrations from a single sample aliquot
has been developed. This technique is based on the hydride
generation atomic absorption (HGAA) spectrophotometry. The hydrides
of the arsenic species are generated in a reaction vessel by mixing
the...
Studies of anisotropic and isotropic Raman line shape yield information about the rotational motion (rotational correlation function) and non-reorientational (vibrational) lifetimes. The rotational motion of carbon disulfide has been studied previously by the techniques of Raman spectroscopy (6, 43), Rayleigh scattering (43, 46) and direct measurement (47). This work was...
The gas phase electron-diffraction (GED) technique has been the primary method used to expand our knowledge and understanding of gas-phase molecular structures. The technique yields interatomic distances and bond angles that are of use in both theoretical and experimental studies.
The GED structural parameters are thermal averages over all vibrational...
The inert gas ion bombardment of solid surfaces has
found many uses in the field of analytical chemistry. In
one method of spectrochemical analysis, inert gas ion
bombardment in a glow discharge is used to produce an atomic
vapor, representative of the sample bulk, which is analyzed
using atomic absorption...
We demonstrate the generation of broadband up-converted multicolor array (BUMA) in a thin BK7 glass slide using two noncollinear weak near-IR laser pulses with various crossing angles. The BUMA signal arises from cubic nonlinear χ⁽³⁾:χ⁽³⁾ processes via cascaded four-wave mixing of the two incident beams. Broad and continuous tunability of...
Ultrafast spectroscopy has recently gained momentum as a powerful, noninvasive characterization toolset capable of studying a diverse array of samples with applications in chemistry, physics, biology, engineering, and more. Two popular ultrafast spectroscopic techniques include femtosecond transient absorption (fs-TA) and femtosecond stimulated Raman spectroscopy (FSRS). The latter of these techniques...
The design and construction of two new sample injection systems or nozzles, for use with the Oregon State electron diffraction apparatus are discussed. One of these nozzles was intended for use with volatile samples the vapors of which were to be heated or cooled over the range -196 to 540°C;...
The synthesis of isoindazoles bearing α-ketoester and α-hydroxyester groups via the coarctate cyclization of ester terminated azo-ene-yne precursors is described. Whereas previous studies on isoindazole formation have shown the reaction to proceed through a kinetic coarctate pathway, functionalization of the terminal acetylene with a methyl ester sufficiently stabilizes the carbene...
In spite of their importance in many systems, liquid surfaces have been
explored at the microscopic level to a much lesser extent than solids. Most surface
analysis must take place in vacuum, a major drawback for liquids. The technique of
time-of-flight scattering and recoil spectrometry (TOF-SARS) has been applied to...
A spectral investigation of the molecular vibration region of
the potassium sulfate crystal system was undertaken. This study was
initiated to establish the feasibility of using this crystal as a
host matrix for ammonium sulfate. Since these two systems are isomorphic
and have unit cells of nearly equal volume the...
A focused Q-switched neodymium-doped glass laser with power
levels ranging from 1-6 MW and with a 50-nsec halfwidth, was used
to vaporize copper metal. Experimental measurements showed that
the amount of material vaporized away from the target was not linear
with laser power and was much less than could be...
An important aspect in device technology is the
processing of GaAs to produce highly-resolved etch
patterns on the substrate. This is done typically on the
GaAs(100) surface. Recently, a number of methods, all
using chlorinated vapor reactants, have been applied to
fabrication of GaAs devices. In spite of these
technological...
The use of semi-volatile organic compounds (SOCs) as molecular markers to identify the contributions of regional and long-range atmospheric transport, as well as current and historic sources, and contaminant deposition in remote ecosystems of the Western U.S. was investigated. Trans-Pacific air masses influenced by Siberian biomass burning events had elevated...
Interesting rovibrational characteristics of two D_(3h) oblate symmetric top molecules were studied. Hamiltonian models for the fine rovibrational level structure of [1.1.1]propellane (propellane) were obtained for many low-lying modes. Ground state parameters (GSP) that are not exclusively K^(2n) dependent were obtained. Initially, the GSP were used in conjunction with density...
In the past decades, femtosecond stimulated Raman spectroscopy (FSRS) has been gaining tremendous popularity in fundamental sciences stemming from chemistry to biology. It is capable of capturing both equilibrium and non-equilibrium structural information across a broad range of timescales with simultaneously high temporal and spectral resolutions. Femtosecond transient absorption spectroscopy...
We report an experimental and theoretical study of single-molecule inner-shell photoemission measured over an extended range of photon energies. The vibrational intensity ratios I (nu = 1)/I (nu = 0) from the C 1s photoelectron spectra of carbon monoxide, although mostly determined by the bond length change upon ionization, are...