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  • 2000-2004  (3)
  • 1995-1999  (7)
  • 1990-1994  (11)
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  • 1
    Electronic Resource
    Electronic Resource
    Electronic spectra of carbon chain anions: C2nH− (n=5–12) (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 9280-9286 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The electronic absorption spectra of mono-hydrogenated carbon chain anions C2nH− (n=5–10) have been measured in the gas-phase and in 6 K neon matrices (n=8–12). The techniques of resonant two-color electron photodetachment in the gas-phase and absorption spectroscopy of mass-selected anions in neon matrix were used. A homologous series is observed, with band system origins shifting from 304 nm for C10H− to 590 nm for C20H−. In conjunction with ab initio calculations the band systems are attributed to a 1Σ+←X 1Σ+ transition of linear acetylenic anions. Another near lying electronic transition due to a second isomer is also apparent for C10H− up to C24H−. Comparison with tables of the known diffuse interstellar bands indicates possible matches for the origin bands of the C18H− and C20H− isomers. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479842
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  • 2
    Electronic Resource
    Electronic Resource
    Mid-infrared spectra of He–HN+2 and He2–HN+2 (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 3876-3885 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Mid-infrared vibrational spectra of He–HN+2 and He2–HN+2 have been recorded by monitoring their photofragmentation in a tandem mass spectrometer. For He–HN+2 three rotationally resolved bands are seen: the fundamental ν1 transition (N–H stretch) at 3158.419±0.009 cm−1, the ν1+νb combination band (N–H stretch plus intermolecular bend) at 3254.671±0.050 cm−1, and the ν1+νs combination band (N–H stretch plus intermolecular stretch) at 3321.466±0.050 cm−1. The spectroscopic data facilitate the development of approximate one-dimensional radial intermolecular potentials relevant to the collinear bonding of He to HN+2 in its (000) and (100) vibrational states. These consist of a short range potential derived from an RKR inversion of the spectroscopic data, together with a long range polarization potential generated by considering the interaction between the He atom and a set of multipoles distributed on the HN+2 nuclei. The following estimates for binding energies are obtained: D0″=378 cm−1 [He+HN+2(000)], and D0′=431 cm−1 [He+HN+2(100)]. While the ν1 band of He2–HN+2 is not rotationally resolved, the fact that it is barely shifted from the corresponding band of He–HN+2 suggests that the trimer possesses a structure in which one of the He atoms occupies a linear proton-bound position forming a He–HN+2 core, to which a second less strongly bound He is attached. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.471244
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  • 3
    Electronic Resource
    Electronic Resource
    The infrared spectrum of the H2–HCO+ complex (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 5152-5164 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A combined experimental and theoretical study of the structural properties of the H2–HCO+ ion-neutral complex has been undertaken. Infrared vibrational predissociation spectra of mass selected H2–HCO+ complexes in the 2500–4200 cm−1 range display several vibrational bands, the most intense arising from excitation of the C–H and H2 stretch vibrations. The latter exhibits resolved rotational structure, being composed of Σ–Σ and Π–Π subbands as expected for a parallel transition of complex with a T-shaped minimum energy geometry. The determined ground state molecular constants are in good agreement with ones obtained by ab initio calculations conducted at the QCISD(T)/6–311G(2df,2pd) level. The complex is composed of largely undistorted H2 and HCO+ subunits, has a T-shaped minimum energy geometry with an H2...HCO+ intermolecular bondlength of approximately 1.75 A(ring). Broadening of the higher J lines in the P and R branches of the Π–Π subband is proposed to be due to asymmetry type doubling, the magnitude of which is consistent with the calculated barrier to H2 internal rotation. The lower J lines in the Σ–Σ and Π–Π subbands have widths of 0.06 cm−1, around three times larger than the laser bandwidth, corresponding to a decay time of ≈90 ps for the upper level. The absence of discernible rotational structure in the ν2 band suggests that it has predissociation lifetime of less than 1 ps. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469240
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  • 4
    Electronic Resource
    Electronic Resource
    The infrared spectrum of the N2H+–He ion-neutral complex (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 5570-5571 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Rotationally resolved, vibrational predissociation spectra of the HN+2–He complex have been recorded in the region of the N–H stretch (3100–3200 cm−1). The complex appears to be linear. Fitting of the measured lines to the pseudodiatomic expression ν=ν0+(B'ν+B‘ν)m +(B'ν−B‘ν–D'ν+D'ν) m2−2(D'ν+D‘ν)m3 −(D'ν−D‘ν)m4 yields the following constants: ν0=3158.419±0.009 cm−1, B‘=0.3517±0.0005 cm−1, D‘=(5.8±0.5)×106 cm−1, B'=0.3579 ±0.0005 cm−1, D'=(3.9±0.6)×106 cm−1. The data support a proton bound He–HNN+ structure, with a 1.72 A(ring) vibrationally averaged intermolecular bondlength, and an approximate intermolecular stretching frequency of 150 cm−1. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469286
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  • 5
    Electronic Resource
    Electronic Resource
    Rotationally resolved A2Πu←X 2Πg electronic transition of NC6N+ (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 924-927 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotationally resolved A2Πu←X2Πg electronic origin band spectrum of dicyanodiacetylene cation, NC6N+, has been recorded in the gas phase using frequency-production double modulation spectroscopy in a liquid nitrogen cooled hollow cathode discharge and cavity ring down spectroscopy in a supersonic plasma. The analysis of the complementary results provides accurate molecular parameters for the two spin-orbit components in both electronic states. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1427710
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  • 6
    Electronic Resource
    Electronic Resource
    Photodetachment spectroscopy of the C2nH− (n=2–4) anions in the vicinity of their electron detachment threshold (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 6126-6131 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The electronic spectra of the C2nH(D)−, n=2–4, anions have been observed in the gas phase using photodetachment spectroscopy. These are assigned to 1Π←X 1Σ+ electronic transitions. The 1Π excited states possess a dipole bound character indicated by the energetic proximity between the origin of the transitions and electron affinities. The dipole bound states are related to the X 2Π ground states of C6H and C8H whereas for C4H, which has an X 2Σ+ ground state, the 2Π is an excited state. Vibronic coupling through a bending motion of the carbon skeleton is inferred to be the reason of the stabilization of this state. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1451248
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  • 7
    Electronic Resource
    Electronic Resource
    Gas phase electronic spectrum of C3H in the visible (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 6913-6919 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The electronic spectrum of C3H has been observed by means of a resonant two color two photon ionization technique sampling a supersonic plasma source. On the basis of ab initio calculations, vibrational and rotational analysis, the complex vibronic system observed in the visible and near UV is assigned to three electronic transitions, A˜ 2A′←X 2Π, B˜ 2A″←X 2Π and C˜ 2A″←X 2Π of C3H. Potential curves along the CCH bending coordinate have been obtained because of its role for the electronic spectrum and dynamics of C3H. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1404391
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  • 8
    Electronic Resource
    Electronic Resource
    The B←X electronic spectrum of N+2–Ne (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 4749-4755 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The electronic spectrum of N+2–Ne has been measured in the region corresponding to the B 2∑+u←X 2∑+g origin and 1–0 transitions of N+2. Spectra were obtained by irradiating a mass selected population of N+2–Ne and monitoring the production of N+2 as a function of wavelength. Low temperature N+2–Ne spectra exhibit several well resolved bands. From the shift of the N+2–Ne origin with respect to that of free N+2 it is apparent that the complex dissociation energy D0 is 146.5 cm−1 greater in the B state than the X state. Pronounced changes in the complex's spectrum occur as the effective temperature is increased. The hottest spectra resemble a broadened and truncated N+2 spectrum. The breaking off at the high energy end of the spectrum at elevated temperatures allows us to establish a rough ground-state dissociation energy of 300 cm−1. Other conclusions resulting from this work are that the equilibrium geometry of the N+2–Ne molecule is probably linear in X and B electronic states, that the ΔG1/2 for the low frequency stretch in the B state is 104 cm−1, and that the N–N stretching motion is affected only very weakly by the presence of the Ne atom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460737
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  • 9
    Electronic Resource
    Electronic Resource
    The B←X electronic spectrum of N2+–He (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 4477-4478 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The electronic spectrum of N2+–He has been measured in the region corresponding to the N2+ B 2Σ+u←X 2Σ+g origin transition. The spectrum was recorded by photoexciting a mass selected beam of N2+–He ions and detecting N2+ fragments. A likely process for the fragmentation involves fluorescence to a vibrationally excited level of the ground electronic state followed by vibrational predissociation. The observed spectrum exhibits well resolved discrete structure and bears a remarkable resemblance to a cold N2+ spectrum suggesting that the potential between the N2+ ion and helium atom in both the X and B electronic states, has at most only a small barrier to internal rotation. Measurement of the shift of N2+–He transitions with respect to the corresponding N2+ lines indicates that the binding energy of the helium atom to the N2+ ion is almost the same in both the B and X electronic states.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458732
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  • 10
    Electronic Resource
    Electronic Resource
    Vibrational predissociation lifetime of N2+–He (X, υ=1) (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 4035-4036 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The B←X spectrum of N+2–He exhibits a hot band which arises from transitions in complexes which have one quantum of the N–N stretching vibration. By measuring the intensity of this peak relative to that of the origin peak as function of the time between ion preparation and laser interrogation we have determined the vibrational predissociation lifetime of the N+2–He complex to be 220±30 μs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.461855
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