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  • 1
    Electronic Resource
    Electronic Resource
    Photodissociation dynamics of the CNN free radical (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 4179-4189 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The spectroscopy and photodissociation dynamics of the A˜ 3Π and B˜ 3Σ− states of the CNN radical have been investigated by fast beam photofragment translational spectroscopy. Vibronic transitions located more than 1000 cm−1 above the A˜ 3Π←X˜ 3Σ− origin were found to predissociate. Photofragment yield spectra for the B˜ 3Σ−←X˜ 3Σ− band between 40 800 and 45 460 cm−1 display resolved vibrational progressions with peak spacing of (approximate)1000 cm−1 corresponding to symmetric stretch 10n and combination band 10n301 progressions. Ground state products C(3P)+N2 were found to be the major photodissociation channel for both the A˜ 3Π and B˜ 3Σ− states. The translational energy distributions for the A˜ 3Π state are bimodal with high and low translational energy components. The distributions for the B˜ 3Σ− state reveal partially resolved vibrational structure for the N2 photofragment and indicate extensive vibrational and rotational excitation of this fragment. These results suggest that bent geometries are involved in the dissociation mechanism and provide more accurate values: ΔfH0(CNN)=6.16±0.05 eV and ΔfH298(CNN)=6.15±0.05 eV. These values, coupled with recent D0(RH) and D298(RH) values from Clifford et al. [J. Phys. Chem. 102, 7100 (1998)], yield ΔfH0(HCNN)=5.02±0.18 eV, ΔfH298(HCNN)=4.98±0.18 eV, ΔfH0(H2CNN)=3.09±0.21 eV, and ΔfH0(H2CNN)=3.09±0.21 eV. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1288267
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  • 2
    Electronic Resource
    Electronic Resource
    Erratum: "Femtosecond stimulated emission pumping: Characterization of the I2− ground state" [J. Chem. Phys. 112, 8847 (2000)] (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 8854-8854 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1318753
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  • 3
    Electronic Resource
    Electronic Resource
    TIME-RESOLVED PHOTOELECTRON SPECTROSCOPY OF MOLECULES AND CLUSTERS (2001)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physical Chemistry 52 (2001), S. 255-277 
    Details
    ISSN: 0066-426X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Time-resolved photoelectron spectroscopy (TRPES) has become a powerful new tool in studying the dynamics of molecules and clusters. It has been applied to processes ranging from energy flow in electronically excited states of molecules to electron solvation dynamics in clusters. This review covers experimental and theoretical aspects of TRPES, focusing on studies of neutral and negatively charged species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.physchem.52.1.255
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  • 4
    Electronic Resource
    Electronic Resource
    Femtosecond photoelectron spectroscopy of I2−(CO2)n clusters (n=4, 6, 9, 12, 14, 16) (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 601-612 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photodissociation dynamics of I2−(CO2)n(n=4–16) clusters excited at 780 nm have been studied with femtosecond photoelectron spectroscopy (FPES). The range of cluster sizes spans the uncaged and fully-caged product limits for this reaction. We observe time scales for a variety of processes in these clusters, including dissociation of the I2− chromophore, solvation of the I− fragment, the onset of recombination on the ground state of I2−, vibrational relaxation, and solvent evaporation. In addition, substantial trapping in a "solvent-separated" state is seen for clusters with n≥9; this state persists for at least 200 ps, the longest time delay probed here. Simulations of the spectra were performed in order to determine the time dependence of the electronic state populations, the I2− vibrational distribution, and the number of CO2 molecules in the cluster. Results are compared to previous experimental and theoretical studies of I2−(CO2)n photodissociation, and to a recent FPES study of I2−(Ar)n clusters. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480685
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  • 5
    Electronic Resource
    Electronic Resource
    Photodissociation dynamics of the triiodide anion (I3−) (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 2255-2262 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The spectroscopy and dissociation dynamics of I3− were investigated using fast beam photofragment translational spectroscopy. The photofragment yield of I3− from 420 to 240 nm was measured, yielding two broadbands at the same energies as in the absorption spectrum of I3− in solution. Photodissociation dynamics measurements performed with two-particle time-and-position sensitive detection revealed two product mass channels having photofragment mass ratios of 1:2 and 1:1. Both channels were seen at all photolysis wavelengths. Translational energy distributions show that the 1:2 products are from a combination of I(2P3/2)+I2− and I*(2P1/2)+I2−. The 1:1 mass channel is from symmetric three-body dissociation to I−+2I. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.482040
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  • 6
    Electronic Resource
    Electronic Resource
    Femtosecond stimulated emission pumping: Characterization of the I2− ground state (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 8847-8854 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Femtosecond stimulated emission pumping in combination with femtosecond photoelectron spectroscopy is used to characterize the potential energy function of the I2−(X˜ 2Σu+) ground state up to vibrational energies within 2% of the dissociation limit. The frequency and anharmonicity of this state are measured at a series of vibrational energies up to 0.993 eV by coherently populating a superposition of ground state vibrational levels using femtosecond stimulated emission pumping, and monitoring the resulting wave packet oscillations with femtosecond photoelectron spectroscopy. The dissociative I2−(A˜′ 2Πg,1/2) state is used for intermediate population transfer, allowing efficient population transfer to all ground state levels. Using the measured frequencies and anharmonicities, the X˜ 2Σu+ state has been fit to a modified Morse potential with the β-parameter expanded in a Taylor series, and the bond length, well depth, and υ=0–1 fundamental frequency set equal to our previously determined Morse potential [J. Chem. Phys. 107, 7613 (1997)]. At high vibrational energies, the modified potential deviates significantly from the previously determined potential. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481499
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  • 7
    Electronic Resource
    Electronic Resource
    Anion photoelectron spectroscopy of I2−(CO2)n(n=1–8) clusters (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 6111-6117 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report the anion photoelectron spectra of I2−(CO2)n clusters (n=1–8) measured at a photon energy of 4.661 eV. Assignment of the spectra is aided by electronic structure calculations on I2−(CO2). The experiment yields size-dependent vertical and adiabatic detachment energies for the formation of the ground state and low-lying valence-excited states of the neutral cluster. Vertical detachment energies are successively blueshifted with increasing cluster size, indicating a stronger stabilization of the anionic cluster relative to the neutral counterpart. In addition, a short progression in the CO2 bending mode is observed in the n=1 and 2 clusters, indicating that the CO2 solvent species are slightly bent (∼2.5°) in the anion clusters. The trends in the total and stepwise solvation energies are discussed in terms of cluster geometries solute–solvent interactions. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1458246
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  • 8
    Electronic Resource
    Electronic Resource
    State-resolved translation energy distributions for NCO photodissociation (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 9020-9027 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photodissociation dynamics of NCO have been examined using fast beam photofragment translational spectroscopy. Excitation of the 102, 301, and 102302 transitions of the B˜ 2Π←X˜ 2Π band produces N(4S)+CO photofragments exclusively, while excitation of the 103303 transition yields primarily N(2D)+CO photoproducts. The translational energy [P(ET)] distributions yield D0(N–CO)=2.34±0.03 eV, and ΔHf,00(NCO)=1.36±0.03 eV. The P(ET) distributions exhibit vibrationally resolved structure reflecting the vibrational and rotational distributions of the CO product. The N(2D)+CO distribution can be fit by phase space theory (PST), while the higher degree of CO rotational excitation for N(4S)+CO products implies that NCO passes through a bent geometry upon dissociation. The P(ET) distributions suggest that when the B˜ 2Π←X˜ 2Π band is excited, NCO undergoes internal conversion to its ground electronic state prior to dissociation. Excitation of NCO at 193 nm clearly leads to the production of N(2D)+CO fragments. While conclusive evidence for the higher energy O(3P)+CN(X 2Σ+) channel was not observed, the presence of this dissociation pathway could not be excluded. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1369132
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  • 9
    Electronic Resource
    Electronic Resource
    Electronic relaxation dynamics of carbon cluster anions: Excitation of the C˜ 2Πg←X˜ 2Πu transition in C6− (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 11185-11192 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Anion femtosecond photoelectron spectroscopy (FPES) has been used to monitor intramolecular electronic relaxation dynamics following the excitation of the C˜ 2Πg←X˜ 2Πu 000 electronic transition in C6−. The time-dependent photoelectron spectra provide a detailed picture of the relaxation dynamics in which the initially excited C˜ 2Πg (v=0) level evolves into highly vibrationally excited C6− in its ground electronic state. The spectra show evidence for a two-step relaxation mechanism: internal conversion (IC) to vibrationally excited B˜ 2Σu+ and A˜ 2Σg+ states, occurring on a time scale of 730±50 fs, followed by IC from these intermediate states to highly vibrationally excited levels in the X˜ 2Πu ground state with a time constant of 3.0±0.1 ps. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1421378
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  • 10
    Electronic Resource
    Electronic Resource
    Photoelectron spectroscopy of GaX2−, Ga2X−, Ga2X2−, and Ga2X3−(X=P,As) (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 4620-4631 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Anion photoelectron spectra taken at various photodetachment wavelengths have been obtained for GaX2−, Ga2X−, Ga2X2−, and Ga2X3− (X=P,As). The incorporation of a liquid nitrogen cooled channel in the ion source resulted in substantial vibrational cooling of the cluster anions, resulting in resolved vibrational progressions in the photoelectron spectra of all species except Ga2X2−. Electron affinities, electronic term values, and vibrational frequencies are reported and compared to electronic structure calculations. In addition, similarities and differences between the phosphorus and arsenic-containing isovalent species are discussed. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1391267
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