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1.
High-order harmonic generations from a one-dimensional Coulomb potential atom are calculated with the initial state prepared as a coherent superposition between its ground and first excited states. When the energy difference of the two states is small, we can choose proper laser pulse such that the first excited state can be excited only to other bound states instead of being ionized. We show that only the hyper-Raman lines are observable instead of the harmonics. The energy difference of the ground and the first excited state can be deduced from the highest peak of the hyper-Raman lines. We further show that the similar results can be obtained by using a combination of two laser pulses with different frequencies interacting with the atom initially at the ground state. 相似文献
2.
《中国光学快报(英文版)》2017,(5)
We investigate the transitions between energy levels and parity symmetry in an effective two-level polar molecule system strongly coupled with a quantized harmonic oscillator. By the dressed-state perturbation theory,the transition diagrams between the dressed-state energy levels are presented clearly and show that the odd(even) parity symmetry is broken by the permanent dipole moment(PDM) of the polar molecules. By the analytical and numerical methods, we find that when the coupling strength and the PDM increase, the more frequency components are induced by the counter-rotating terms and PDM. 相似文献
3.
D. Messnarz G.H. Guthöhrlein 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(2):269-282
The hyperfine structure of about 200 lines of the neutral tantalum atom was investigated by means of Doppler limited laser
spectroscopy. From the spectra we have deduced the magnetic hyperfine interaction constants A and the electric quadrupole interaction constants B of 8 levels with even parity and 81 levels with odd parity. Further, we have discovered 24 new levels of even parity and
11 new levels of odd parity. 相似文献
4.
本文研究了单电子分子离子与强激光场相互作用下的高次谐波发射谱。从光谱中观察到除了存在入射激光频率奇数倍的谐波谱线外,还存在其他频率的超拉曼谱线。在理论上阐明了超拉曼谱线不同于高次谐波谱线的物理产生机制。研究发现当体系初态为基态和较高激发态的叠加态时能够较清晰的观察到超拉曼谱线,从而说明激发态电子的布居对超拉曼谱线的产生起着关键作用。因此在实验上,制备一个叠加态使得电子从激发态电离,是观察到超拉曼谱线的重要条件。 相似文献
5.
K. Shamim I. Siddiqui L. Windholz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,64(2-3):209-220
We present 39 odd and 15 even parity newly discovered fine structure levels of Pr I with low angular momentum: J = 1/2, 3/2 and 5/2. Spectral lines in the range 4200 Å to 7500 Å were experimentally investigated using laser induced fluorescence spectroscopy in a hollow cathode discharge lamp. The levels were discovered by analysis of the recorded hyperfine patterns of the investigated transitions. With the help of these levels, 119 spectral lines were classified directly by laser excitation and 127 lines were classified as fluorescence lines. 相似文献
6.
We calculate the harmonic spectrum generated by a model HD molecule in a strong laser pulse. The unequal nuclear masses lead to the emission of even harmonics, i.e., photon frequencies which are even multiples of the laser frequency. The effect does not occur within the Born-Oppenheimer approximation. In the high-frequency region, the even harmonics are almost of the same order of magnitude as the odd ones. 相似文献
7.
Abstract Hyper-Raman scattering (HRS), first theoretically predicted by Decius and Rauch in 1959 [l] and experimentally demonstrated by Terhune et al. in 1965 [2], is a nonlinear optical process involving two incident photons (ω0) and one emitted photon (ω). The emitted hyper- Raman photon frequencies are Raman-shifted relative to the second harmonic frequency (2ω0) of the incident laser radiation [3–6]. The energy difference (2ω0 – w) corresponds to one of the characteristicvibrational frequencies of the scattering medium or molecule. In Fig. 1 is given a schematic illustration of resonant and nonresonant HRS. The primary advantage of this nonlinear optical technique lies in its more relaxed selection rules compared with IR and Raman [7,8]. AlllR-active vibrational modes are hyper-Raman allowed, and those modes inactive in both IR and Raman (i.e., the “silent” modes) may be active in hyper-Raman scattering. 相似文献
8.
Berthold-Georg Englert Nicoletta Sterpi Herbert Walther 《Optics Communications》1993,100(5-6):526-535
An experiment to determine the parity of the photon field of one privileged mode in a high-Q resonator is proposed. Even parity indicates that the photon number equals zero, two, four or any other even integer; likewise, odd parity states are mixtures of states with any odd number of photons. The parity measurement can be performed while the resonator is pumped as in standard one-atom maser operation. The time dependence of the parity expectation value is studied theoretically, and we suggest its experimental verification, which would serve as a test of the standard models describing both the relaxation of the cavity field toward thermal equilibrium and the pumping process. The connection between parity expectation values and Wigner's phase space function is recalled; the central value of the Wigner function equals twice the mean parity and it is, therefore, a measurable quantity. 相似文献
9.
通过数值求解激光驱动下电子在一维周期势场中运动的薛定谔方程,研究了晶体在激光场中发射的低阶谐波强度随激光波长的变化规律,结果表明,晶体发射低阶谐波强度随激光波长的变化规律与晶体发射高次谐波第一平台区域的变化规律不同.已有的研究表明晶体发射高次谐波第一平台区域的强度会随激光波长的增加而衰减,而我们发现晶体发射低阶谐波的强度会随激光波长的增加而增加.通过对晶体发射低阶谐波的时频分析、晶体价带能量变化与激光光子能量的关系,解释了晶体发射低阶谐波强度随激光波长增加而增加的原因. 相似文献
10.
11.
N. Jaritz H. Jäger L. Windholz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):267-276
We have classified about 200 new lines and have discovered 13 energy levels with even parity and 1 level with odd parity by
means of the systematic hyperfine structure investigation of a large number of spectral lines of the neutral tantalum atom.
For the new levels we deduced their angular momenta, parity and magnetic hyperfine interaction constants A as well as the electric quadrupole interaction constants B.
Received 8 August 2001 相似文献
12.
S. Kröger 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(1):55-59
Laser spectroscopy with either optogalvanic or laser
induced fluorescence detection have been employed to measure the
hyperfine structure of 25 transitions of atomic niobium in the
visible and near infrared spectral range. The magnetic dipole
hyperfine interaction constants A of 43 energy levels (22 of
even and 21 of odd parity) were determined, 30 of which have been
investigated for the first time. The values obtained for the even
parity levels are compared with the results of a parametric
analysis. 相似文献
13.
14.
S. Kröger I. K. Öztürk F. G. Acar G. C. Başar G. Başar J.-F. Wyart 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(1):61-70
A parametric analysis of the fine and the magnetic dipole hyperfine structure
for the three configurations of odd parity 4d35s5p, 4d45p and
4d25s25p was performed.
Effective one-electron parameters were determined and
theoretical predictions are given for the magnetic dipole
hyperfine structure constants A
for the levels of these three configurations.
Additionally,
12 new energy levels could be found, four of odd and eight of even parity,
by re-analysing data for experimental wavelengths of Nb. 相似文献
15.
16.
We present a very simple scheme for generating four-qubit cluster
states with one step using parity measurement based on
dipole-induced transparency in a cavity-waveguide system. The scheme
only uses the photon detectors to check the parity of the spatially
separated dipole, which are the same (even parity) or different (odd
parity) through measuring the light fields in the waveguide. The
initial entangled states remain after nondetective identification
and they can be used for successive tasks. 相似文献
17.
Generation of non-integer high-order harmonics and significant enhancement of harmonic intensity
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《中国物理 B》2021,(4)
High-order harmonics from helium atom in the orthogonally two-color(OTC) laser field are investigated by solving the two-dimensional time-dependent Schrodinger equation.Non-integer high-order harmonics are obtained in some ratio of frequencies of two components.Pure odd and even harmonics from atoms could be separated in two components by adjusting the ratio of frequencies in OTC scheme,and the resolution of harmonics is improved at the same time.The physical mechanism is explained by the periodicity of dipole.With the same intensity of the incident laser,the intensity of the high-order harmonics from the OTC field scheme is improved by three orders of magnitude compared to the monochromatic laser field scheme.A theoretical scheme is provided for experimentally achieving improving energy resolution and separation of pure odd and even harmonics in atoms.Also,we provide a means for improving harmonic intensity. 相似文献
18.
19.
The masses of the nonstrange baryon resonances in quark model with spin-spin and tensor interactions
M. Böhm 《Zeitschrift fur Physik C Particles and Fields》1980,3(4):321-328
We calculate the masses of the nonstrange baryon resonances from a quark model with Coulomb and linear potential and hyperfine interaction. We treat the nonrelativistic problem with help of the variational method, the matrix of the spin-spin and tensor force is diagonalized within a harmonic oscillator supermultiplet. We find for the even and odd parity resonances good agreement with the spectrum of the particle data group and the results of the Karlsruhe-Helsinki phase shift analysis. 相似文献
20.
通过数值求解二维含时薛定谔方程,理论研究了正交偏振双色激光场作用下H2+分子高次谐波发射和孤立阿秒脉冲的产生. 数值结果显示,改变激光场的强度比,可以调控高次谐波强度以及谐波椭偏率. 结果表明随着场强比的增加,y方向的谐波强度不断提高. 当场强比为1:2.5时,x方向和y方向分别仅有奇次谐波和偶次谐波产生,并且偶次谐波的强度比奇次谐波强度高2-3个数量级. 此时,奇次谐波的椭偏率最大可以达到0.3,偶次谐波的椭偏率接近于0. 此外,通过改变分子的准直角可以控制谐波的椭偏率,基于这一现象,利用椭圆偏振高次谐波的平台区合成了椭偏率为0.05的椭圆偏振阿秒脉冲链. 相似文献