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  • 1
    Electronic Resource
    Electronic Resource
    Electron spin resonance investigations of aluminum hydrides (AlH2, AlHD, AlD2), and aluminum hydroxides (Al(OH)2, and Al(OD)2) in neon matrixes at 4 K; comparisons with ab initio theoretical calculations (1993)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 97 (1993), S. 1304-1311 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100109a010
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  • 2
    Electronic Resource
    Electronic Resource
    Electron spin resonance and theoretical studies of the 14N⋅⋅⋅⋅14N and 15N⋅⋅⋅⋅15N spin-pair radicals in neon matrices: The effects of mixing among the 1Σg+, 3Σu+, 5Σg+, and 7Σu+ electronic states (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 3145-3154 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The first experimental and theoretical study of the N⋅⋅⋅⋅N spin-pair radical is reported. Its high-resolution ESR (electron spin resonance) spectrum has been observed in neon matrices and interpreted on the basis of weakly interacting atoms using a model recently developed for the H⋅⋅⋅⋅H spin-pair. To fully interpret the N⋅⋅⋅⋅N radical results it was necessary to include electronic state mixing effects among all possible spin states, namely the 1Σg+, 3Σu+, 5Σg+, and 7Σu+ states. Several different trapping sites were observed which indicated the interaction of N atoms at distinctly different separation distances in the neon lattice. Calculated J values at the complete active space self-consistent field (CASSCF) level (TZP basis set) were compared with the experimental results for the various trapping site distances. The 15N⋅⋅⋅⋅15N radical in the dominant trapping site had magnetic parameters of g=2.0016(2), A(15N)=15.9(1) MHz, D=−178(1)MHz and J=468(2) MHz. Using the point dipole approximation this corresponds to a N⋅⋅⋅⋅N separation distance of 6.41 Å. A most unusual type of magnetic dipole transition was observed that involves a transition between electronic states of formally different S values where S is the total spin quantum number for a given electronic state. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479594
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  • 3
    Electronic Resource
    Electronic Resource
    Electron spin resonance studies of 45Sc17O, 89Y17O, and 139La17O in rare gas matrices: Comparison with ab initio electronic structure and nuclear hyperfine calculations (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 5658-5669 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The first nuclear hyperfine measurements of 17O (I=5/2) have been made for Sc17O, Y17O and La17O in their X 2Σ ground electronic states. These metal oxide radicals were generated by the pulsed-laser vaporization of the metals in the presence of 16O2/17O2 and trapped in neon and argon matrices for electron spin resonance investigations. The fully resolved A tensors of the metal and 17O were compared with ab initio theoretical calculations—a comparison previously reported only for the ScO radical. The computational methods employed were unrestricted Hartree–Fock, density functional theory (DFT), and restricted open-shell Hartree–Fock. Having the metal and 17O hyperfine interactions available has permitted a more thorough description of the electronic structure and charge distribution in these metal oxide molecules. An electronic structure comparison with the AlO, GaO, and InO radicals has also been made. Reasonably good agreement between the observed and calculated values of Aiso and Adip were achieved with the DFT method providing the closest agreement. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.478464
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  • 4
    Electronic Resource
    Electronic Resource
    Theoretical and electron spin resonance studies of the H(centered ellipsis)H, H(centered ellipsis)D, and D(centered ellipsis)D spin-pair radicals in rare gas matrices: A case of extreme singlet–triplet mixing (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 1409-1424 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The H(centered ellipsis)H, H(centered ellipsis)D, and D(centered ellipsis)D spin-pair radicals have been thoroughly investigated in neon, argon, krypton, and xenon matrices near 4 K by electron spin resonance (ESR). A theoretical model has been developed that treats these spin-pairs as weakly interacting atoms. The model includes the effects of 3Σ/1Σ mixing in the analysis of the observed ESR spectral results and yields a consistent set of magnetic parameters for these three isotopomers in all four rare gas hosts. The consideration of H atoms interacting with other H atoms over a distribution of internuclear distances in the rare gas lattice is included in the theoretical and experimental analyses. Application of the model to earlier ESR results for H(centered ellipsis)CH3 reveals a value for its Heisenberg exchange interaction (J) which is found to be considerably larger than that for the H(centered ellipsis)H spin-pair. The effects of methane and neon on the J value are calculated for these spin-pairs. The H(centered ellipsis)H case is unusual in that the nuclear hyperfine interaction (A) is considerably larger than D (the anisotropic dipole–dipole magnetic interaction between electrons) which is much larger than J. The H(centered ellipsis)H spin-pairs exhibit internuclear distances greater than 7 Å and have the following magnetic parameters (MHz) based upon this model of "weakly interacting atoms;" giso=2.0016, Aiso=1426, D=−200, and J=6. Since a distribution of distances is involved, other spin-pairs would be separated by even greater distances in the matrix and thus have smaller absolute values of D and J. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.476714
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  • 5
    Electronic Resource
    Electronic Resource
    Electron spin resonance matrix isolation studies of 27Al16,17O, 69,71Ga16,17O and 115In16,17O: Observed hyperfine interactions compared with ab initio theoretical results (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 7011-7019 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Electron spin resonance (ESR) studies are reported for Al16,17O, Ga16,17O, and In16,17O isolated in neon matrices at 4 K. Except for Al16O, no previous ESR measurements have been reported for these X 2Σ diatomic radicals. The pulsed laser vaporization of the metals in the presence of 16O2 and 17O2 produced high quality ESR spectra of these metal oxide radicals whose nuclear hyperfine interactions (A tensors) were fully resolved for both the metal and oxygen nuclei. An analysis of the experimental spin densities in combination with different types of theoretical calculations provided detailed information concerning the electronic structure trends going down this metal oxide group. Increased p-orbital spin density on oxygen was observed for the heavier metal oxide radicals. Nonrelativistic ab initio calculations with an extended basis set and the UB3LYP method reproduced the trends in the isotropic and dipolar hyperfine interactions. All-electron CI calculations, restricted open-shell Hartree–Fock (ROHF) wave functions, and unrestricted Hartree–Fock wave functions gave results very different from experiment and from each other for the isotropic interaction. All calculations were in fair agreement with each other for the dipolar interaction and provided an assignment of the sign for that term. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.475164
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  • 6
    Electronic Resource
    Electronic Resource
    Group theoretical study of the radical cation of methane: The effect of tunneling motions on the hyperfine interaction (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 3367-3376 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The electron spin resonance (ESR) spectrum of CH+4 indicates that some large amplitude tunneling motions among Jahn–Teller distorted structures make the four protons equivalent. A group theoretical study using the permutation–inversion (PI) group is performed to analyze the hyperfine interaction of the nonrigid CH+4. It is shown that three patterns of the interaction are possible depending upon the type of tunneling motions. Only one of the three patterns is consistent with the experimental spectrum, which is presented in the accompanying paper [J. Chem. Phys. 103, 3377 (1995)]. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.470221
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  • 7
    Electronic Resource
    Electronic Resource
    Electron spin resonance and theoretical studies of the PO2 and AsO2 radicals in neon matrices at 4 K: Laser vaporization and x-irradiation radical generation techniques (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 497-505 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The utilization of high energy generation techniques for trapping ion radicals and other reactive intermediates in neon matrices at 4 K is discussed. Electron spin resonance (ESR) results for several small radicals are presented to demonstrate the application of x irradiation and reactive laser vaporization for neon matrix isolation studies. Detailed ESR studies of the PO2 and AsO2 radicals, along with ab initio theoretical computations of their nuclear hyperfine interactions, are presented. No previous ESR observations have been reported for these radicals, although PO2 has been studied under high resolution in the gas phase utilizing far-infrared laser magnetic resonance and microwave spectroscopies. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.470135
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  • 8
    Electronic Resource
    Electronic Resource
    An electron spin resonance investigation of vanadium dioxide (51V16O2 and 51V17O2) and 51V17O in neon matrices with preliminary assignments for VO3 and V+2: Comparison with ab initio theoretical calculations (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 10237-10250 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The first spectroscopic characterization of the VO2 radical is reported along with new results for V17O and tentative assignments for the VO3 and V+2 radicals. These vanadium radicals were investigated in neon matrices at 4 K by electron spin resonance utilizing conventional high temperature vaporization and pulsed laser ablation generation methods. A detailed ESR study of VO2 showed it to be nonlinear with a 2A1 ground state; the g tensor analysis reveals the presence of an excited electronic state (2B1) approximately 1 eV above the ground state. This excited state prediction and the observed nuclear hyperfine interactions (A tensors) for 51V and 17O were compared with theoretical results obtained from various ab initio computational methods. Ab initio calculations with an extended basis set were performed at various levels of theory including UHF, ROHF, CAS-SCF, and MR-SDCI (multireference single and double configuration interaction). While UHF calculations of the hyperfine interaction were grossly in error, the better levels of theory gave qualitative agreement with experiment and provided an aid to interpretation. VO2 is predicted to be a bent 2A1 state, correlating with the linear 2Δ configuration having the odd electron predominantly in the V 3d orbital. VO3 is predicted to be planar C2v, with the odd electron in a b2 orbital localized in the oxygen in-plane n-type p orbitals. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472953
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  • 9
    Electronic Resource
    Electronic Resource
    Electron spin resonance matrix isolation and ab initio theoretical investigations of 69,71GaH2, 69,71GaD2, H69,71GaCH3, and D69,71GaCD3 (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 6607-6615 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: First time electron spin resonance studies are reported for various isotopomers of GaH2 and HGaCH3. The radicals were generated in neon matrices at 4 K by the ultraviolet photoexcitation of Ga which undergoes insertion reactions with H2 and CH4. Ab initio calculations with a large uncontracted basis and configuration interaction with all single excitations from the spin-restricted Hartree–Fock configuration gave good agreement with the experimental results and supported the free atom comparison method interpretation of the hyperfine interactions. A comparison with similar radicals is presented, including BH2, AlH2, HAlCH3, HAlOH, and AlH+. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471974
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  • 10
    Electronic Resource
    Electronic Resource
    Electron spin resonance rare gas matrix studies of 12CO2−, 13CO2−, and C17O−2: Comparison with ab initio calculations (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 5672-5686 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The 12C16O2−, 13C16O2−, 12C17O2−, and 12C16,17O2− radical anions have been generated by four independent methods and isolated in neon and argon matrices for detailed ESR (electron spin resonance) investigations. Included with these experimental measurements for the various magnetic parameters of CO−2 are high level ab initio calculations (MR SD-CI and others) of the 13C and 17O hyperfine A tensors. Some of the calculations included the effects of a 42-atom neon cage on the electronic structure of CO−2. Previous ESR studies of CO−2 have been conducted in more perturbing environments, such as ionic crystals, where the close proximity of the counter cation can alter the anion's properties. A comparison of the earlier measurements in more interactive materials with these theoretical and rare gas matrix results reveals a significantly different distribution of the spin density. The neon magnetic parameters (MHz) for CO−2 are gx=2.0018, gy=1.9964, gz=2.0010; for 13C, Ax=320.4, Ay=296.1, Az=394.5; for 17O, Ax=−81.6, Ay=−74.9 and Az=−151.8. The argon results are similar to these neon values; isotropic spectra in argon were also observed at elevated temperatures that yielded giso and Aiso parameters consistent with the low temperature (4 K) anisotropic spectra. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472456
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