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We both experimentally and theoretically demonstrated that molecular rotational populations can be actively controlled in a coherent rotational wave packet by using two strong, properly delayed femtosecond laser pulses.

We propose a strategy to achieve laser-field-free molecular orientation with the combination of an electrostatic field and an intense, nonresonant laser field with rapid turn off. The adiabatically created pendular state is effectively transferred to the rotational wave packet in the nonadiabatic regime after the rapid turn off of the laser pulse and the orientation achieved at the peak of the laser pulse is revived at the rotational period of the molecule with the same degree of orientation. The remarkable difference in molecular behavior is found between alignment and orientation, which reveals the crucial importance of the sufficiently long rising time of the laser pulse to achieve the highest possible degree of orientation. The feasibility has been examined for OCS molecules as a sample under practical experimental conditions.

We experimentally observed revival signals of high-order harmonics under field-free molecular alignment by applying chirp-free and chirped laser pulses. The revival signal obtained even with chirp-free laser pulses exhibited linearly dependant spectral phase with respect to frequency, and the slope of the spectral phase changed with the laser chirp condition.

We introduce a new tool to control the nonadiabatic alignment dynamics in asymmetric top molecules. Alignment is induced using nonresonant, linearly polarized laser pulses with pulse durations that are short compared to the rotational periods of the molecule. Through a series of nonresonant Raman transitions a rotational wave packet is created. It is concluded with an interesting connection between the duration of the alignment pulse and the wave packet dynamics, providing a new tool to transform the non-periodic revival structure of an asymmetric top, into stable periodic rotations about the C-axis of the molecule. The experimentally observed features are also reproduced qualitatively in numerical simulations.

Selective alignment by femtosecond pulses of molecules in multi-component mixtures is shown to be a powerful tool for the detection, identification, and separation of chemically close species.

Rotational wavepacket dynamics produced by a ultrafast pulses are related to linear and nonlinear optical susceptibilities. Limitations of wavepacket dynamic probing through optical susceptibilities are revealed. Correlations between nonlinear order and fractional revivals are discussed.

We image the dynamics of diatomic and triatomic molecules with sub-$5\phantom{\rule{0.3em}{0ex}}\mathrm{fs}$ and sub-\AA{} resolution using laser Coulomb explosion imaging with $8\phantom{\rule{0.3em}{0ex}}\mathrm{fs}$ pulses. We obtain image information by measuring the vector momenta of all atomic ions produced by explosion of a single molecule. We image vibrating $\mathrm{D}_{2}{}^{+}$ and of dissociating $\mathrm{S}\mathrm{O}_{2}{}^{2+}$ and $\mathrm{S}\mathrm{O}_{2}{}^{3+}$. Images taken at 0 and $60\phantom{\rule{0.3em}{0ex}}\mathrm{fs}$ show that the dissociation of $\mathrm{S}\mathrm{O}_{2}{}^{2+}$ produces an $\mathrm{S}{\mathrm{O}}^{+}$ rotational wave packet.

High-order harmonic generation is demonstrated to provide a sensitive way for an extensive study of dynamic processes in the field-free alignment of strong-field-induced molecular rotational wave packets. The time-dependent harmonic signal observed from field-free-aligned N-2, O-2, and CO2 has been found to include two sets of beat frequency for pairs of coherently populated rotational states. One of them is the well-known frequency component characterizing the field-free alignment of molecules, and the other is ascribed to the beat that arises from coherence embedded in the wave packet. We discuss the effect of each frequency component on the revival signal observed with the harmonic generation.

State-selective phase control over rotational wave packets in two Li2 electronic states using tailored femtosecond pulses is demonstrated. A shaped preparation pulse simultaneously creates wave packets in the A and E electronic states, which are probed using a second time-delayed pulse. This allows independent phase control of selected rotational wave packet components in both electronic states.bl]References

We demonstrate experimentally how the time-dependent phase modulation induced by molecular rotational wave packets can manipulate the phase and spectral content of ultrashort light pulses. Using impulsively excited rotational wave packets in ${\mathrm{CO}}_{2}$, we increase the bandwidth of a probe pulse by a factor of 9, while inducing a negative chirp. This chirp is removed by propagation through a fused silica window, without the use of a pulse compressor. This is a very general technique for optical phase modulation that can be applied over a broad spectral region from the IR to the UV.

Rotational wave packet revivals on an excited electronic state have been measured by femtosecond time-resolved photoelectron imaging for the first time. The first full revival at 82 ps of S1 (n,pi*) pyrazine was clearly observed in the time dependencies of the photoelectron intensity and the photoelectron angular distribution (PAD). The PAD, measured for laser aligned pyrazine, clearly reflects the different characters of pi* and 3s molecular orbitals.

The coherent control of molecular orientation by a terahertz few-cycle laser pulse is theoretically studied. It is demonstrated that the field-free molecular orientation results from the interference contributions between the odd and even rotational wave packet, and therefore the constructive and destructive interferences lead to the observation of the positive and negative orientations, corresponding to the positive and negative degrees. Furthermore, the enhancement or suppression of the molecular orientation can be coherently manipulated by precisely controlling the carrier-envelope phase of the terahertz few-cycle pulse.

We propose a scheme to achieve field-free molecular orientation by a nonresonant square laser pulse. Using CO molecules as an example, we show that, differing from the conventional Gaussian pulse, field-free molecular orientation excited by square pulses can be realized in both nonadiabatic and adiabatic cases. We also show that the maximum degree of the molecular orientation can be further enhanced by separating one square pulse into two time delayed subpulses and by applying the second subpulse at the beginning of the rotational wave packet rephrasing created by the first subpulse and the optimal intensity ratio between the two subpulses is about I1/I2 = 1 : 1.5.

Further expressions are given which relate the rotational constants of the rigid asymmetric rotator to experimental data through moments of the energy levels. These expressions remove the requirement that all energy levels for given J be known. Instead, the energy levels associated with one symmetry group of the rotational wave functions for given J are required.

The variations in velocity of dilatational waves in the pressure range 0 to 15,000 lb./in.2 and temperature range 30° to 90°C have been measured for samples of polystyrene, Lucite, and polyethylene. The velocity of rotational waves was also measured for polystyrene and Lucite. In polyethylene no trace of a rotational wave could be identified. The elastic moduli and Poisson's ratio are computed over the experimental range.

The dilatational and rotational wave velocities have been measured as functions of pressure and temperature for three gabbros, two basalts and a dunite. The pressure range was 200–6,000 bars. The temperature range was 25° to 300°C. and 400°C. for one sample. The maximum pressure is equivalent to 23 km of depth and the highest temperature is believed to correspond to 25 km. The data indicate a tendency for the velocity to reach a maximum somewhere between 10 and 20 km and then decrease slightly.

The effects of inelastic excitations on the /sup 22/Ne(p,t)/sup 20/Ne reaction are investigated. Differential cross sections at a proton energy of 39.9 MeV were measured for /sup 22/Ne(p,t)/sup 20/Ne transitions to the 0+, 2+, and 4+ members of the ground-state rotational band, to the 2- and 3- members of the excited K/sup / pi / = 2 band; and to the 0+ and 2+ members of the first excited K/sup pi / = 0/sup +/ band. The cross sections to membees of the ground- state band are compared with distorted-wave Born-approximation (DWBA) and coupled- channel-Born-approximation (CCBA) calculations using both pure Nilsson and pairing-mixed Nilsson rotational wave functions. Only the CCBA calculation with pairing provides a reasonable description of the experimentaal data. The effects of multistep processes are found to be as large for neon as for rare=earth nuclei. The shape and relative strengh of the measured cross section to the 2- state, a transition which is forbidden by a direct single-step process, are reproduced well by the CCBA calculation, which allows the excitation of the 2- state by inelastic processes in the entrance and exit channels. (auth)

By using the Laplace transform method, solution has been obtained for the elastodynamic problem due to blast pulse on the inner surface of a spherical cavity in an infinite spherically aeolotropic elastic solid. Both types of blast producing radial and rotational waves have been considered.

The dilatational and rotational wave velocities have been measured as functions of pressure and temperature for five granites. The pressure range was 200-5,000 bars or higher. Dilatational velocities were measured over the temperature range 20-300 degrees C.; rotational wave velocities over the range 20-200 degrees C. These data indicate that below fairly shallow depths in the granitic layer the velocity is constant or even slightly decreasing.

The theory of the interactions of hindered internal rotation with over‐all rotations is extended to include nonrigid asymmetric rotors. The interdependence of hindered internal rotation and vibrations and their effect upon the vibrational energy levels is considered. The theory is developed analogously to the theory developed for symmetric rotors in a previous paper. An approximate over‐all internal rotational wave function of the form 1/(2π)½ exp[i(PzIz2/Iz —τ)]φr is discussed, where φr is the wave function that diagonalizes the rigid rotor Hamiltonian and τ is an integer.While the general energy relation involves too many parameters to compute or to fit empirically, certain special cases are discussed. In particular for the 000→101 transition of the CH3NO2 type of molecule one has ν(000→101)=(101|〈H〉R|101)[1+F1(m|1−cos3θ|m)+G2(m|Π2|m)]+2G3(m|Π2|m)+2F2(m|1−cos3θ|m), where (101|〈H〉R|101) is the rigid rotor energy for the 101 level, Θ is the angle of internal rotation, II is the internal angular momentum, ...

Our considerations are pointed to a role of microstructure in a geological space and especially in that region of Earth interior where earthquakes are occuring. It seems that internal structure and discontinuities hare an essential influence on development of geophysical processes. Moreover, it is resonable to believe that the conception of continuum with microstructure can be a suitable tool to describe the earthquake phenomena and wave propagation in the near focal zone.

Elastic constants of selected rocks and minerals are listed, as obtained from measured values of density and of compressional and rotational wave velocities along three orthogonal directions. Density‐velocity correlation and velocity‐anisotropy are discussed.

The regions of deformed nuclei are characterized in particular by the occurrence of low — lying rotational bands which very nearly obey the following rule $${{\rm{E}}_{\rm{I}}} = {{{\hbar ^{\rm{2}}}} \over {2I}}{\rm{I}}\left( {{\rm{I + 1}}} \right)$$ (1)

In this paper, we have given a method for calculating non-axial rotational wave functions and energy levels of odd-A nuclei by means of that of even-even nuclei.

We compare the differential cross section at a proton energy of 39.8 MeV for the transition ${\mathrm{Ne}}^{22}(p,t){\mathrm{Ne}}^{20}$ (${2}^{\ensuremath{-}}$, 4.97 MeV), which is forbidden by the usual selection rules for a single-step process, with a coupled-channel Born-approximation calculation using rotational wave functions of the adiabatic form. The calculated results are in good agreement with the experimental data.