ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Hydration of carbon dioxide: The structure of H2O–H2O–CO2 from microwave spectroscopy (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 106-117 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The structure of the gas-phase trimeric complex H2O–H2O–CO2 is determined through an analysis of the rotational spectra of ten isotopically substituted species. These spectra were measured in the region between 7.5 and 18 GHz using a pulsed-molecular-beam Fourier-transform microwave spectrometer. The nondeuterated species display two sets of transitions separated by ∼1 MHz. The splittings of the perdeuterated form are smaller and three partially deuterated forms have no splittings. The rotational constants for the lower frequency set of transitions of the normal species are A=6163.571(4) MHz, B=2226.157(2) MHz, C=1638.972(1) MHz, δJ=0.000 83(3) MHz, ΔJ=0.002 98(4) MHz, ΔJK=−0.0005(2) MHz. The differences in the rotational constants between the upper and lower states are ΔA=498 kHz, ΔB=520 kHz, and ΔC=−133 kHz. The dipole moments are μa=1.571(5) D and μb=0.761(4) D with μc=0 D. The dipole moments and the intertial defect of −0.620 uA(ring)2 both indicate an essentially planar complex. The structure is found to be cyclical with the dimer-type bond lengths within the trimer being approximately the same as those found in the free heterodimers. One water molecule is oxygen bound to the carbon atom of the CO2 and is also hydrogen bonded to the oxygen of the second water molecule. The second water molecule is in turn hydrogen bonded to one of the oxygens of the CO2 molecule. The observed splittings are most likely due to a hydrogen-exchanging internal rotation of this second water molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460384
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Water hydrogen bonding: The structure of the water–carbon monoxide complex (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 7095-7109 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Rotational transitions between J≤3 levels within the K=0 manifold have been observed for H2O–CO, HDO–CO, D2O–CO, H2O–13CO, HDO–13CO, and H217O–CO using the molecular beam electric resonance and Fourier transform microwave absorption techniques. ΔMJ=0→1 transitions within the J=1 level were also measured at high electric fields. A tunneling motion which exchanges the equivalent hydrogens gives rise to two states in the H2O and D2O complexes. The spectroscopic parameters for H2O–CO in the spatially symmetric tunneling state are [∼(B0) =2749.130(2)MHz, D0=20.9(2)kHz, and μa=1.055 32(2)D] and in the spatially antisymmetric state are [∼(B0) =2750.508(1)MHz, D0=20.5(1)kHz, and μa=1.033 07(1)D]. Hyperfine structure is resolved for all isotopes. The equilibrium structure of the complex has the heavy atoms approximately collinear. The water is hydrogen bonded to the carbon of CO; however the bond is nonlinear. At equilibrium, the O–H bond of water makes an angle of 11.5° with the a axis of the complex; the C2v axis of water is 64° from the a axis of the complex. The hydrogen bond length is about 2.41 A(ring). The barrier to exchange of the bound and free hydrogens is determined as 210(20) cm−1 (600 cal/mol) from the dipole moment differences between the symmetric and antisymmetric states. The tunneling proceeds through a saddle point, with C2v structure, with the hydrogen directed towards the CO subunit. The equilibrium tilt away from a linear hydrogen bond is in the direction opposite to the tunneling path.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458250
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Erratum: The structure of the CO2–CO2–H2O van der Waals complex determined by microwave spectroscopy [J. Chem. Phys. 90, 5964 (1989)] (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 5166-5166 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458622
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The structure of the CO2–CO2–H2O van der Waals complex determined by microwave spectroscopy (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 5964-5970 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Rotational spectra of CO2 –CO2 –H2 O, CO2 –CO2 –D2 O, 13 CO2 –13 CO2 –H2 O and CO2 –CO2 –H2 18 O have been measured using a pulsed-molecular-beam Fabry–Perot Fourier-transform microwave spectrometer. An asymmetric top spectrum is observed with rotational constants, A=3313.411(5) MHz, B=1470.548(3) MHz, and C=1308.850(3) MHz for the normal species. The dipole moment obtained is μT =μb =1.989(2) D. Only b-type transitions are observed with the transitions showing a 3 to 1 intensity alternation depending on whether Ka +Kc is odd or even, respectively. This indicates a structure with twofold symmetry with the C2v axis of the water subunit aligned with the C2 axis of the complex. The CO2 subunits lie in a plane which is perpendicular to the C2 axis and located 2.47 A(ring) below the oxygen atom of the water subunit; the C–C bond length is 3.413(2) A(ring). The orientation of the CO2 subunits in CO2 –CO2 –H2 O is very similar to that observed in CO2 –CO2 although the C–C bond length is 0.19 A(ring) shorter in the trimer. The C–O bond distances between the H2 O and two CO2 subunits are both 3.00(2) A(ring) which is 0.16 A(ring) longer than that found in the CO2 –H2 O dimer. The hydrogens of the H2 O subunit are directed away from the CO2 –CO2 plane although their angular orientation around the b axis is not well determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456362
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The structure and internal dynamics of CO–CO–H2O determined by microwave spectroscopy (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 7807-7816 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational spectra of CO–CO–H2O, CO–CO–HDO, 13CO–CO–H2O, and 13CO–13CO–H2O have been measured using a pulsed-molecular-beam Fabry–Perot Fourier-transform microwave spectrometer. The complex exhibits internal motion involving an exchange of the CO subunits as well as an hydrogen exchange. In the normal species this is indicated in the spectrum by transition doublets separated by a few hundred kHz and an effective shift of alternating transitions which prevents a good semirigid rotor fit. The other isotopically substituted complexes have spectra in which the transitions are either singlet, doublet or quartets depending on the appropriate spin weights or because of dampening of the internal motion. All the spectra are mutually consistent with a tunneling path with four isoenergetic states. By treating the tunneling frequency of the CO interchange as a vibrational frequency, the rotational constants of two internal rotor states and a tunneling frequency could be determined. The tunneling frequency in CO–CO–H2O is 372 kHz and the ground state rotational constants are A=4294.683(70) MHz, B=1685.399(35) MHz, C=1205.532(35) MHz. The tunneling frequency corresponding to the hydrogen exchange is not determined but the observed transition splittings are comparable to those found for other van der Waals complexes containing a water subunit. The dipole moments determined for CO–CO–HDO are μa=4.790(87)×10−30 C m [1.436(26) D], μb=1.79(12)×10−30 C m [0.533(35) D], and μc=1.10(37)×10−30 C m [0.33(11) D]. The general structure of the complex is found to be cyclic. The CO–CO configuration is approximately T-shaped with the carbon atom of one subunit directed toward the molecular axis of the other subunit. The H2O subunit has a hydrogen atom directed toward the CO subunits but not in the expected linear hydrogen bonded configuration. The uncertainties given in parentheses are one standard deviation. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.468981
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Water–hydrocarbon interactions: Structure and internal rotation of the water–ethylene complex (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 725-732 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational spectra of C2H4–H2O and C2H4–D2O were measured using the molecular beam electric resonance technique. The rotational and centrifugal distortion constants obtained for C2H4–H2O are: B+C=7274.747 (24), B−C=371.103 (8), A=25 858.4 (36), ΔJ=0.0279 (17), ΔJK=1.7352 (66), and δJ=0.002 99 (22) MHz. The dipole moment for both isotopic species is 1.094 (1) D. The structure derived from an analysis of the rotational constants and dipole moment is nonplanar with Cs symmetry. The water molecule is singly hydrogen bonded perpendicular to the plane of the ethylene; i.e., into the π system. The plane of the water bisects the C–C bond. The hydrogen bond length is 2.48 A(ring). Splittings are observed in the rotational transitions of C2H4–H2O but not in C2H4–D2O. These are assigned to excited torsional levels of the hindered internal rotation of the water with respect to the ethylene. The barrier height is estimated to be V2=1.0±0.2 kcal/mol which is surprisingly high for this weakly bound complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451279
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    The microwave spectrum of the K=0 states of Ar–NH3 (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 5512-5518 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The microwave spectrum of Ar–NH3 has been obtained using molecular beam electric resonance spectroscopy and pulsed nozzle Fourier transform microwave spectroscopy. The spectrum is complicated by nonrigidity and most of the transitions are not yet assigned. A ΔJ=1, K=0 progression is assigned, however, and from it the following spectroscopic constants are obtained for Ar–14NH3: (B+C)/2=2876.849(2) MHz, DJ =0.0887(2) MHz, eqQaa =0.350(8) MHz, and μa =0.2803(3) D. For Ar–15NH3 we obtain (B+C)/2 =2768.701(1) MHz and DJ =0.0822(1) MHz. The distance between the Ar atom and the 14NH3 center of mass RCM is calculated in the free internal rotor limit and obtained as 3.8358 A(ring). In the pseudodiatomic approximation, the weak bond stretching force constant is 0.0084 mdyn/A(ring) which corresponds to a weak bond stretching frequency of 35 cm−1. The NH3 orientation in the complex is discussed primarily on the basis of the measured dipole moment projection and the quadrupole coupling constant. It is concluded that the Ar–NH3 intermolecular potential is nearly isotropic and that the NH3 subunit undergoes practically free internal rotation in each of its angular degrees of freedom. Spectroscopic evidence is presented which indicates that the NH3 subunit also inverts within the complex. These conclusions concerning the internal dynamics in the Ar–NH3 complex support the model initially proposed in our previous study of the microwave and infrared spectra of this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451562
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    The rotational spectra of NH3–CO and NH3–N2 (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 2472-2480 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational spectra of NH3–CO, ND3–CO, ND2H–CO, NDH2–CO, NH3–13CO, and NH3–N2 have been measured by molecular beam electric resonance. The K=0 ground vibrational state transitions for these species were fit to a linear molecule Hamiltonian and the following constants were obtained for NH3–CO; (B+C)/2 (MHz)=3485.757(2), DJ (kHz)=110.2(2), eQqNaa (MHz)=−1.890(7), μa (D)=1.2477(8). These constants were also determined forND3–CO [3078.440(7), 75.7(8), −2.028(15), 1.2845(9)], NHD2–CO [3202.303(4), 86.8(6), −1.972(11), 1.2686(8)], NH2D–CO [3338.235(4), 98.9(6), −1.916(12), 1.2546(8)], NH3–13CO [3451.684(5), 108.7(7), −1.870(15), 1.2452(8)]. For NH3–N2 (B+C)/2=3385.76(21), DJ =117.(10), and μa =1.069(14). For NH3–CO three ||ΔJ||=1, K=0 progressions were seen along with two ||ΔJ||=1, K=1 progressions, suggesting nonrigidity in the complex. The internal rotation of the NH3 subunit about its C3 axis is expected to be essentially free, but this motion, by itself, is not sufficient to explainthe observed spectra, thus, large amplitude dynamics are occurring in at least two degrees of freedom. The quadrupole coupling constants, eQqNaa indicate that in each of the isotopes of NH3–CO the NH3 subunit has its C3 axis relatively rigidly oriented at an angle of approximately 36° with respect to the line connecting the centers of mass of the two subunits. The structure is not hydrogen bonded; the N atom is closest to the CO subunit. The orientation of the CO subunit is not established. The distance between the N atom and the center of mass of the CO unit (RN–CO) is 3.54(3) A(ring). The spectroscopic constants suggest that the weak bond stretching force constant is quite small (0.01 mdyn/A(ring)) but compatible with the long bond length.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450366
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Water in weak interactions: The structure of the water–nitrous oxide complex (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 2861-2868 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational spectra of H2O–N2O, D2O–N2O, and HDO–N2O have been observed using molecular beam electric resonance techniques at both zero and nonzero electric fields. H2O–N2O is nonrigid with respect to internal rotation of the water subunit. Rotational constants in MHz for the spatially antisymmetric tunneling state are A=12 605.001(77), B=4437.978(32), and C=3264.302(32). Rotational constants for the spatially symmetric tunneling state are A=12 622.595(203), B=4437.422(47), C=3264.962(47). These together with the rotational constants of the other isotopomers are consistent with a planar, T-shaped arrangement of the heavy atoms of the complex, with the distance between the centers of mass of the two subunits, Rc.m., equal to 2.91(2) A(ring) or a distance of 2.97(2) A(ring) from the H2O oxygen to the central nitrogen of N2O. The measured dipole moments of the two tunneling isomers are identical; μa = 1.480(2) and μb = 0.31(2) D. The values of these dipole moment components indicate an in-plane equilibrium tilt of about 20° between the C2v axis of water and the N–O weak bond. This tilt suggests a second interaction may exist between a hydrogen on water and the N2O subunit. The rotational constants suggest that the N2O unit is tilted by about 9° from perpendicular to the N–O weak bond. The barrier for the tunneling interchange of the water protons is estimated to be 235(10) cm−1. Quadrupole coupling constants eqQaa for the outer and inner nitrogen of N2O are 0.371(130) and 0.128(45) MHz, respectively. Electrostatic models applied to water–N2O and water–CO2 predict hydrogen bonded structures rather than the experimentally observed Lewis base structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463028
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...