Electronic structure and time-dependent description of rotational predissociation of LiH

Adiabatic potential energy curves of the $^1\Sigma^+$ and $^1\Pi$ states of the LiH molecule have been calculated. They correlate asymptotically to atomic states, like 2s+1s, 2p+1s, 3s+1s, 3p+1s, 3d+1s, 4s+1s, 4p+1s and 4d+1s. Very good agreement is found between our calculated spectroscopic parameters and experimental ones. The dynamics of the rotational predissociation process of the $1^1\Pi$ state has been studied by solving the time-dependent Schr\"{o}dinger equation. The classical experiment of Velasco [Can. J. Phys. {35}, 1204 (1957)] on dissociation in the $1^1\Pi$ state is explained in detail

Electronic structure and rovibrational predissociation of the 2sPi state in KLi

Adiabatic potential energy curves of the 3sSigma+, 3tSigma+, 2sPi and 2tPi states correlating for large internuclear distance with the K(4s) + Li(2p) atomic asymptote were calculated. Very good agreement between the calculated and the experimental curve of the 2sPi state allowed for a reliable description of the dissociation process through a small (20 cm-1 for J = 0) potential energy barrier. The barrier supports several rovibrational quasi-bound states and explicit time evolution of these states via the time-dependent nuclear Schroedinger equation, showed that the state populations decay exponentially in time. We were able to precisely describe the time-dependent dissociation process of several rovibrational levels and found that our calculated spectrum match very well with the assigned experimental spectrum. Moreover, our approach is able to predict the positions of previously unassigned lines despite their low intensit

Disorder mediated splitting of the cyclotron resonance in two-dimensional electron systems

We perform a direct study of the magnitude of the anomalous splitting in the cyclotron resonance (CR) of a two-dimensional electron system (2DES) as a function of sample disorder. In a series of AlGaAs/GaAs quantum wells, identical except for a range of carbon doping in the well, we find the CR splitting to vanish at high sample mobilities but to increase dramatically with increasing impurity density and electron scattering rates. This observation lends strong support to the conjecture that the non-zero wavevector, roton-like minimum in the dispersion of 2D magnetoplasmons comes into resonance with the CR, with the two modes being coupled via disorder.Comment: accepted to PRB Rapid Com

Infrared spectroscopy of Landau levels in graphene

We report infrared studies of the Landau level (LL) transitions in single layer graphene. Our specimens are density tunable and show \textit{in situ} half-integer quantum Hall plateaus. Infrared transmission is measured in magnetic fields up to B=18 T at selected LL fillings. Resonances between hole LLs and electron LLs, as well as resonances between hole and electron LLs are resolved. Their transition energies are proportional to $\sqrt{B}$ and the deduced band velocity is $\tilde{c}\approx1.1\times10^6$ m/s. The lack of precise scaling between different LL transitions indicates considerable contributions of many-particle effects to the infrared transition energies.Comment: 4 pages, 3 figures, to appear in Phys. Rev. Let