Volume 122, Issue 11, 15 March 2005
Index of content:
122(2005); http://dx.doi.org/10.1063/1.1876212View Description Hide Description
Recent experimental and theoretical methods allowed the efficient investigation of highly excited rovibrational states of molecular systems. At these levels of excitation the correspondence principle holds, and then classical mechanics can provide intuitive views of the involved processes. In this respect, we have recently shown that for completely hyperbolic systems, homoclinic motions, which are known to organize the classical chaotic region in Hamiltonian systems, imprint a clear signature in the corresponding highly excited quantum spectra. In this Communication we show that this result also holds in mixed systems, by considering an application to the floppy molecular system.
122(2005); http://dx.doi.org/10.1063/1.1885468View Description Hide Description
Molecular dynamics simulations of model bilayers made of amphiphilic chain molecules dissolved in a Lennard-Jones solvent, reveal a new transition between a flat tensioned state and a foamy rough thick compressed bilayer. Variation of lateral tension with area per surfactant head undergoes unexpected and dramatic changes when the system size is substantially increased; a new transition is then found. Scaling is discussed and structure factor is reported.
Electronic and vibrational spectra of the low-lying state of 4-dimethylaminobenzonitrile: Comparison of theoretical predictions with experiment122(2005); http://dx.doi.org/10.1063/1.1889431View Description Hide Description
Comparison of the TD-BP86∕cc-pVDZ electronic excitation energies and the CIS∕cc-pVDZ vibrational frequencies of 4-dimethylaminobenzonitrile with the available experimental data indicates that the picosecond transient absorption at about 700 nm, and the excited-state vibration of frequency , belong to the lowest-energy state of bent geometry (CCN bond angle of about 120° and a large CN bond distance). Consistent with these assignments, the Raman band, attributed to the CN stretch, exhibits a large resonance enhancement of intensity when the probe (Raman excitation) wavelength is set to the spectral region of the absorption. The result corroborates the occurrence of an ultrafast state switch from the initially excited state to the state of lower energy.
122(2005); http://dx.doi.org/10.1063/1.1883634View Description Hide Description
Quantum coherent vibrational relaxation of an impurity strongly coupled to its solid host is demonstrated through four-wave mixing measurements to infer sustained coherence in the bath, which is recognized as a superposition of macroscopically distinct states.