Browsing by Author "Lin, C. D."

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Analysis of angular dependence of strong-field tunneling ionization for CO(2)
(2009-11-01)
Zhao, Song-Feng
;
Jin, Cheng
;
Le, Anh-Thu
;
Jiang, T. F.
;
Lin, C. D.
We analyzed the discrepancy of the angular dependence of strong-field ionization for CO(2) among the different theoretical calculations and experiments. Using a more accurate ground-state wave function of CO(2) in the asymptotic region, we showed that the accuracy in the earlier tunneling ionization theory of Tong [Phys. Rev. A 66, 033402 (2002)] is much improved. We also concluded that the angular dependence deduced from the experiment of Paviccicacute [Phys. Rev. Lett. 98, 243001 (2007)] appears to be too narrowly distributed.
Analysis of angular dependence of strong-field tunneling ionization for CO2
(2009-11-01)
Zhao, Song-Feng
;
Jin, Cheng
;
Le, Anh-Thu
;
Jiang, T. F.
;
Lin, C. D.
We analyzed the discrepancy of the angular dependence of strong-field ionization for CO2 among the different theoretical calculations and experiments. Using a more accurate ground-state wave function of CO2 in the asymptotic region, we showed that the accuracy in the earlier tunneling ionization theory of Tong [Phys. Rev. A 66, 033402 (2002)] is much improved. We also concluded that the angular dependence deduced from the experiment of Paviccicacute [Phys. Rev. Lett. 98, 243001 (2007)] appears to be too narrowly distributed.
Determination of structure parameters in strong-field tunneling ionization theory of molecules
(2010-03-01)
Zhao, Song-Feng
;
Jin, Cheng
;
Le, Anh-Thu
;
Jiang, T. F.
;
Lin, C. D.
In the strong field molecular tunneling ionization theory of Tong et al. [Phys. Rev. A 66, 033402 (2002)], the ionization rate depends on the asymptotic wave function of the molecular orbital from which the electron is removed. The orbital wave functions obtained from standard quantum chemistry packages in general are not good enough in the asymptotic region. Here we construct a one-electron model potential for several linear molecules using density functional theory. We show that the asymptotic wave function can be improved with an iteration method and after one iteration accurate asymptotic wave functions and structure parameters are determined. With the new parameters we examine the alignment-dependent tunneling ionization probabilities for several molecules and compare with other calculations and with recent measurements, including ionization from inner molecular orbitals.
Gravity-assisted chemical vapor deposition of vertically aligned single-walled carbon nanotubes
(2007)
Yeh, C. M.
;
Chen, M. Y.
;
Gan, J.-Y.
;
Hwang, J.
;
Lin, C. D.
Temperature and CH4/H-2 ratio of gas-flow rates are the two factors that strongly affect the qualities of vertically aligned single-walled carbon nanotubes (SWCNTs) in gravity-assisted chemical vapor deposition (CVD). The qualities of SWCNTs and other carbon products grown by gravity-assisted CVD were characterized by scanning electron microscopy and Raman spectroscopy. At temperatures between 850 and 900 degrees C, SWCNTs of very good quality stand alone on the substrate. At other temperatures, nanofibers or irregular islands of carbon are present on the substrate. The CH4/H-2 ratio influences the quality of SWCNTs more abruptly than temperature. At low ratio, no carbon nanotube is formed. The window of CH4/H-2 ratio for the growth of vertically aligned SWCNTs ranges from 160:80 to 160:40. At a ratio higher than 160:40, multiwalled CNTs replace SWCNTs and become the dominant product. (C) 2007 The Electrochemical Society.
Theory of probing attosecond electron wave packets via two-path interference of angle-resolved photoelectrons
(2010-07-15)
Choi, N. N.
;
Jiang, T. F.
;
Morishita, T.
;
Lee, M. -H.
;
Lin, C. D.
We study theoretically the electron wave packet generated by an attosecond pulse train (APT) which is probed with a time-delayed infrared (IR) laser pulse. The APT creates an excited state and a continuum electron wave packet. By ionizing the excited state with an IR, a delayed new continuum electron wave packet is created. The interference of the wave packets from the two paths, as reflected in angle-resolved photoelectron spectra, is analyzed analytically. Using the analytical expressions, we examine the possibility of retrieving information on the electron wave packet generated by the APT.