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1.
Anion Mass Spectrometry Study of Ion-Pair Photodissociation of CO2 in the XUV Energy 19.70-22.24eV 下载免费PDF全文
We demonstrate anion mass spectrometry using the Hefei synchrotron radiation source to investigate the ion-pair dissociation processes of molecules. The efficiency curve of the O^- anionic product via ion-pair dissociations of CO2 is recorded with tunable extreme vacuum ultraviolet photons (energy: 19.70-22.24 eV) and compared with the spectrum available in the literature. The possible dynamics of CO2 + hv → CO^++ O^- in this energy range is discussed. 相似文献
2.
Erratum: Photodissociation Efficiency Spectroscopy Study of the Rydberg Excited Ion-Pair States of Carbon Dioxide 下载免费PDF全文
In our paper published on Chinese Physics Letters 26(2009)103401, there were some mistakes in Table 1. Here is the corrected table: 相似文献
3.
Lifetimes of different vibronic levels at high excess energies in the S1 state of isolated benzene molecules are measured using for the first time a two-photon ionization pump–probe technique with
UV femtosecond pulses. For the 6113 state (3290 cm-1 excess energy) at the onset of the ‘channel three’ a biexponential decay is found with a fast (τf=20 ps) and a slow (τs>500 ps) component. The values are in line with previous sub-Doppler high-resolution measurements of this band in our laboratory.
We explain the measured faster decay (τf=900 fs, τs=100 ps) of the 71 state at a lower excess energy of 3077 cm-1 by a simultaneous excitation of the adjacent 61
013
0161
1 hot band leading to a vibronic state of higher excess energy and faster decay. The vibronic levels 6114 and 7111 at a higher excess energy of ≳4000 cm-1 show a biexponential decay of τf=550 fs, τs=30 ps and τf≲300 fs, τs=20 ps, respectively. The experimental results point to dynamic processes within the vibronic level manifold of the S1 state and a fast nonradiative electronic relaxation process.
Received: 3 November 1999 / Published online: 5 July 2000 相似文献
4.
Selective control over the vibrational excitation and space quantization of the dissociation fragments by optimally designed
linearly polarized and shaped infrared (IR) laser pulses of the picosecond (ps) and subpicosecond duration is demonstrated
by means of quantum-dynamical simulations within the Schr?dinger wave-function formalism for a three-dimensional (3-D) model
of HONO2 in the ground electronic state, wherein the OH and the ON single-bond stretches are explicitly treated, together with the
bending angle between them, on the basis of the ab initio defined 3-D potential-energy surface and dipole function. The high-lying
zeroth-order vibrational states of the OH bond are prepared selectively both below and above the dissociation threshold of
the ON single bond, and demonstrate a quasi-periodic oscillatory behaviour, manifesting intramolecular vibrational energy
redistribution (IVR) on the picosecond timescale. Selective breakage of the ON single bond in HONO2 with more than 97% probability is demonstrated, along with control of the space quantization of the dissociation fragments:
the OH fragments rotating clockwise, OH(c), and anticlockwise, OH(a), are prepared selectively, with the OH(a)/OH(c) branching
ratio being as high as 10.975. The results obtained show that optimally designed strong and short IR-laser pulses can compete
against IVR and manipulate vibrational excitation and dissociation of polyatomic molecules.
Received: 3 November 1999 / Published online: 13 July 2000 相似文献
5.
Using rate equations the effect of different pulse sequences, pulse durations, and delay times of two lasers on ionization probability and selectivity in resonant two-step photoionization of molecules is investigated. The results demonstrate to what extent a given selectivity of the absorption or relaxation of the intermediate electronic, state is influenced by a special combination of these parameters. 相似文献
6.
Using a representation of multichannel quantum defect theory in terms of a quantum Poincaré map for bound Rydberg molecules, we apply Jung's scattering map to derive a generalized quantum map, that includes the continuum. We show that this representation not only simplifies the understanding of the method, but moreover produces considerable numerical advantages. Finally we show under what circumstances the usual semi-classical approximations yield satisfactory results. In particular we see that singularities that cause problems in semi-classics are irrelevant to the quantum map. 相似文献
7.
X. P. Tang A. Becker W. Liu S. M. Sharifi O. G. Kosareva V. P. Kandidov P. Agostini S. L. Chin 《Applied physics. B, Lasers and optics》2005,80(4-5):547-557
Occurrence and influence of several self-action effects, induced in the entrance window of a time-of-flight interaction chamber, on the ion and fragment yields of the toluene molecule in the focus of a Ti:sapphire laser pulse are analyzed. Experimental data are obtained using different focusing geometries and are compared with results from numerical simulations using a nonlinear pulse propagation model as well as those from the strong-field S-matrix theory. It is shown that (a) self-focusing leads to a displacement of the focus while amplified small perturbations of the input beam result in hot spots in the spatial distribution and in an energy-dependent focus area, (b) small self-phase modulation changes the form of the spectrum and broadens it slightly. A strong increase of the toluene fragmentation appears to correlate to linear and nonlinear changes in the focal spot area, while the scenario of excitation of Raman modes proposed in an earlier publication is ruled out as the dominant effect.This revised version was published online in March 2005. In the previous version, the published online date was missing 相似文献
8.
S. Guizard D. Chapoulard M. Horani D. Gauyacq 《Applied physics. B, Lasers and optics》1989,48(6):471-477
Resonantly enhanced multiphoton ionization (REMPI) is proposed as an ultrasensitive detection method forreal-time monitoring of atmospheric pollutants in situ. The technique is demonstrated in the laboratory for NO diluted in pure nitrogen at 560 mbar. The MPI current resulting from (2+1) photon ionization of NO via the resonantC
2
H (v=0) state has been measured for several NO concentrations. Detection levels as low as 50 ppt have been obtained.Laboratoire associé à l'Université de Paris-Sud 相似文献
9.
We present a detailed derivation of the Ammosov-Delone-Krainov theory of tunnel ionization in complex systems (CS-ADK). A few mistakes in the previous works have been found and corrected. The theory is then applied to CO2, showing that CS-ADK yields better agreement with experiment than the molecular ADK theory. 相似文献
10.
Photoelectron angular distributions (PADs) from above-threshold ionization of O2 and N2 molecules irradiated by a bichromatic laser field of circular polarization are studied. The bichromatic laser field is specially modulated such that it can be used to mimic a sequence of one-cycle laser pulses. The PADs are greatly affected by the molecular alignment, the symmetry of the initial electronic distribution, and the carrier-envelope phase of the laser pulses. Generally, the PADs do not show any symmetry, and become symmetric about an axis only when the symmetric axis of laser field coincides with the symmetric axis of molecules. This study shows that the few-cycle laser pulses can be used to steer the photoelectrons and perform the selective ionization of molecules. 相似文献
11.
Theoretical Study of the Influence of Femtosecond Laser Wavelength on the Evolution of a Double-Minimum Electronic Excited State Wave Packet for NaRb 下载免费PDF全文
Employing the two-state model and the time-dependent wave packet method, the influence of femtosecond laser wavelength on the evolution of the double-minimum electronic excited state wave packet is numerically investigated. For different laser wavelengths, evolutions of the double-minimum electronic excited state wave packet with time and internuclear distance are different. One can control the evolution of the wave packet by varying the laser wavelength appropriately, which will benefit the light manipulation of atomic and molecular processes. Furthermore, study of the dynamics of the NaRb molecule may yield clues to creating an ultracold molecule. 相似文献
12.
Study on Non-Sequential Double Ionization of Aligned Diatomic Molecules in Strong Laser Fields 下载免费PDF全文
We develop a semiclassical model to describe the non-sequential double ionization of aligned diatomic molecules in an intense linearly polarized field. It is found that in the tunnelling regime, the oriented molecule shows geometric effects on double ionization process when aligned parallel and perpendicular to the external field. Our results are qualitatively consistent with the recent experimental observations. 相似文献
13.
本文研究了Rb(5^2P) He(Ar) nhv→Rb(7^2D) He(Ar) n-1)hv过程,激光频率调离Rb7D5/2→5P3/2跃迁谱线20-100cm^-1,测量了精细结构普线强度分支出I(7D3/2→5P1/2)/I(7D5/2→5P3/2)。测量结果表明,原相互作用势和非绝热效应在分子离解动力学中起关键作用。 相似文献
14.
J. Diebel H. Löwe P. Samorí J.P. Rabe 《Applied Physics A: Materials Science & Processing》2001,73(3):273-279
The IR double-resonance techniques IR/R2PI (infrared/resonant 2-photon ionization), IR/PIRI (infrared-photo-induced Rydberg
ionization) and IR-photodissociation spectroscopy are valuable tools to investigate structure, vibrations, and dynamical processes
of neutral and ionic hydrogen-bonded clusters containing aromatic molecules. In this paper we report on the application of
the IR double-resonance techniques to determine the NH and OH stretching vibrations of 4-aminophenol and 4-aminophenol(H2O)1, both in the neutral (S0) and ionic (D0) ground state. All vibrational frequencies obtained for 4-aminophenol and the cluster are compared with the values obtained
from ab initio and DFT calculations. In the S0 state, a trans-linear arrangement of 4-aminophenol(H2O)1 is obtained containing an O-H·· O hydrogen bond. In the D0 state an overlay of two spectra can be observed resulting from the trans-linear structure and a second structure which contains
a N-H·· O hydrogen bond. The observation of these two structures within the ion is an interesting example of a rearrangement
reaction in the ionic state.
Received: 3 November 2000 / Accepted: 6 November 2000 / Published online: 9 February 2001 相似文献
15.
K. Thomson M. Ziskind C. Mihesan E. Therssen C. Focsa 《Applied Surface Science》2007,253(15):6435-6441
Characterization of polycyclic aromatic hydrocarbons (PAHs) samples has been performed by laser desorption combined with multi-photon ionization technique using two different geometries of the ionization laser beam. This comparative study evidences the strong influence of ionization laser fluence on PAH fragmentation. Through a ∼103 enlargement of the ionization probe volume and 104 reduction of laser fluence over previous studies, fragment free mass spectra are obtained with higher sensitivity and selectivity. The ability to measure fragment free PAH mass spectra is a very important step in the end goal of measuring complex unknown mixtures of PAH desorbed from solid surface such as soot samples. 相似文献
16.
H. P. Liu Z. G. Sun S. D. Hogan N. Q. Lou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(3):357-362
We report an experimental study of the multiphoton dissociation dynamics of
CF3I performed on a home-built femtosecond laser pump-probe system, with
time-of-flight mass spectrometer. The first repulsive A band and the
5pπ37sσ υ2=1 Rydberg state of CF3I were accessed
by one- and two-photon transitions at 267 nm, respectively, with the latter
two-photon absorption followed by a further two-photon probe transition at
401 nm to the
state of the parent ion. The observed signals
from the CF3
+ and I+ fragments show similar multi-component
exponential decay patterns but the former is 4 times stronger than the
latter. However, the parent CF3I+ signal was observed to evolve in a
very different manner, decreasing sharply when probed in the first 289 fs
following excitation and subsequently rising again after 860 fs to a
constant level below that measured at negative pump-probe delay times when the
pump and probe pulses exchange roles. This dip observed in the parent ion
profile, is very different from that previously reported at shorter pump
wavelengths of 264 nm or 265 nm, and is interpreted as the competition
between two different ionization channels. One from the vibrationally excited
υ2=1 of the irradiated Rydberg state and the other from the
dissociative vibrational origin of the same electronic state which is
populated by internal vibrational relaxation. 相似文献
17.
Fragmentation of CO in a linearly polarized femtosecond laser field within the intensity order of 10^14 W.cm^-2 at 820nm is investigated experimentally by using velocity mapping technique. According to the observed kinetic energy and angular distributions of different charged fragment ions, fragmentation channels of CO are proposed. The angular distributions provide helpful information for assigning the dissociation channels. 相似文献
18.
19.
K. Osvay I. N. Ross C. J. Hooker J. M. D. Lister 《Applied physics. B, Lasers and optics》1994,59(3):361-365
A detailed investigation of laser-generated nonlinear processes of undoped barium fluoride is presented including two-photon-excited exciton fluorescence, color-center formation and damage-threshold measurements. A single-shot autocorrelator based on two-photon fluorescence of BaF2 was constructed to measure the phase and amplitude of pulses provided by large apeture excimer lasers. The capabilities of the autocorrelator are demonstrated at 248 nm and 268 nm with pulses in the regime of 100 fs to 10 ps. 相似文献
20.
The angular distributions of CO^+ from the dissociation of CO2^2+ and CO2^+ in intense femtosecond laser fields (45 fs, about 5 × 10^15 W/cm^2) are studied at a laser wavelength of 800nm based on the time-of-flight mass spectra of CO^+ fragment ions. The experimental results show that structural deformation occurs in the charge state of CO2^2+ and the CO^+ maintains linear geometrical structure. 相似文献