Hindered and modulated rotational states and spectra of adsorbed diatomic molecules

Shih, Yu-Tai; Chuu, Der–San; Mei, W.

doi:10.1103/physrevb.54.10938

Cited by 13 publications

(18 citation statements)

References 41 publications

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“…Experimental and theoretical investigations of the rotational distribution of scattering or desorbing molecules have been an active research field. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] The measured rotational-state distributions of molecules scattering or desorbing from surfaces were found to exhibit a substrate temperature-independent non-Boltzmann feature. [1][2][3] On the other hand, the theoretical studies on the rotational motion of adsorbed molecules have been also reported.…”

Section: Introductionmentioning

confidence: 94%

“…Together with the sudden unhindrance approximation, the non-Boltzmann property of the rotational-state distributions can be attributed to the hindered rotations of adsorbed molecules. In our previous works, [8][9][10] we proposed a finite-conical-well model to generalize the study of a finite hindrance. Our results showed that the rotational-state distributions of desorbing molecules are non-Boltzmann and display oscillatory structures with alternate drops and plateaus.…”

Section: Introductionmentioning

confidence: 99%

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Rotational states of an adsorbed dipole molecule in an external electric field

2003

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The rotational states of an adsorbed dipole molecule in an external electric field were investigated. The surface hindering potential was modeled as a finite conical well and a dipole-field interaction was added to the hindering potential. The molecular wave functions were expressed in terms of the eigenfunctions of molecular hindered rotation in the absence of electric field. Eigenenergies were determined by the matrix diagonalization procedures. Our results showed that, for both vertically and horizontally adsorbed molecules, there is avoided crossing between two adjacent rotational energy levels, as the field strength is increased, and finally all state energies decrease rapidly as the field strength is strong enough. The avoided crossing is due to the redistribution of wave function between different potential well regions. By employing the sudden unhindrance approximation, the rotational-state distributions of molecules desorbing from a solid surface in the presence of external electric field were calculated. Our results showed that the rotational-state distributions are significantly influenced by the external electric field. Since the electric field increases the ground-state energy of adsorbed molecule, the distribution shifts towards the high-J region if the electric field is applied to orient the molecular axis against the molecular preferred orientation. On the contrary, the distribution shifts towards the low-J region if the electric field is applied to orient the molecular axis towards molecular preferred orientation because the electric field decreases the ground-state energy of adsorbed molecule. The solutions to the finite conical well were also used to calculate the rotational alignment in the photodesorption of CO from Cr 2 O 3 (0001). Our results showed that at low-J values the CO molecules desorb like a helicopter, while at high-J values a cartwheel-like motion is preferred. This result is in qualitative agreement with the experimental observation.

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Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Rotational states of an adsorbed dipole molecule in an external electric field

2003

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“…Substituting for q ÿV 0 =4B and a E=B 2q we obtain the well known Mathieu's equation [15]. Its eigenenergies are shown in Fig.…”

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confidence: 99%

Fullerene Quantum Gyroscope

et al. 2004

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We report the observation of quantized rotational states of a diatomic C2 unit in solid endohedral fullerene C(2)Sc(2)@C(84). The rotational transitions induce a periodic line pattern in the low energy Raman spectrum. The rotational constant B and the C-C distance were found to be 1.73 cm(-1) and 0.127 nm, respectively. Density functional calculations revealed an intrinsic rotational barrier of the order of only a few meV for the C2 unit. The Schrödinger equation involving the potential barrier was solved and the Raman tensor matrix elements were calculated, yielding good quantitative agreement with the experiment. To our best knowledge this is the first intrinsic rotational spectrum of a diatomic plane molecular rotor.

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“…The two experiments denote measurements of rotational properties of molecules desorbing from a surface. To capture the properties of molecular desorption, the rotational-state distribution and quadrupole moment are calculated on the basis of the conical-well model [29,36]. The theoretical results suitably agree with the experimental observations [17,34,35].…”

Section: Resultsmentioning

confidence: 50%

Orientation of adsorbed molecules under the influence of electric fields

Liao

2015

Molecular Physics

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The dynamic orientation of vertically adsorbed polar molecules is investigated by switching on electric fields. The rotational properties of molecules are modulated by the electric field and the conical well. The orientation reveals multiple pronounced oscillations, depending on the specific field parameters. The range of oscillation is enhanced even in the presence of conical-well confinement. Furthermore, population concentration and inversion cyclically occur in the system, corresponding to distinctive molecular orientations. Specific field-free orientation is also obtained by turning off the field. The population can be concentrated or reversed for a long time. The thermal effect on the properties of orientation is analysed in detail.

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Hindered and modulated rotational states and spectra of adsorbed diatomic molecules

Cited by 13 publications

References 41 publications

Rotational states of an adsorbed dipole molecule in an external electric field

Rotational states of an adsorbed dipole molecule in an external electric field

Fullerene Quantum Gyroscope

Orientation of adsorbed molecules under the influence of electric fields

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