Faraday modulation spectrometry of nitric oxide addressing its electronic X2Π - A2Σ+ band: I. Theory.

We give a simple two-transition model of Faraday modulation spectrometry (FAMOS) addressing the electronic X(2)Π(ν('') = 0) - A(2)Σ(+)(ν(') = 0) band in nitric oxide. The model is given in terms of the integrated line strength, S, and first Fourier coefficients for the magnetic-field-modulated dispersive line shape function. Although the two states addressed respond differently to the magnetic field (they adhere to the dissimilar Hund coupling cases), it is shown that the technique shares some properties with FAMOS when rotational-vibrational Q-transitions are targeted: the line shapes have a similar form and the signal strength has an analogous magnetic field and pressure dependence. The differences are that the maximum signal appears for larger magnetic field amplitudes and pressures, ∼1500 G and ∼200 Torr, respectively.

Spectral method for the time-dependent Gross-Pitaevskii equation with a harmonic trap.

We study the numerical resolution of the time-dependent Gross-Pitaevskii equation, a nonlinear Schrödinger equation used to simulate the dynamics of Bose-Einstein condensates. Considering condensates trapped in harmonic potentials, we present an efficient algorithm by making use of a spectral-Galerkin method, using a basis set of harmonic-oscillator functions, and the Gauss-Hermite quadrature. We apply this algorithm to the simulation of condensate breathing and scissor modes.

Optimal molecular alignment and orientation through rotational ladder climbing.

We study the control by electromagnetic fields of molecular alignment and orientation in a linear, rigid-rotor model. With the help of a monotonically convergent algorithm, we find that the optimal field is in the microwave part of the spectrum and acts by resonantly exciting the rotation of the molecule progressively from the ground state, i.e., by rotational ladder climbing. This mechanism is present not only when maximizing orientation or alignment, but also when using prescribed target states that simultaneously optimize the efficiency of orientation/alignment and its duration. The extension of the optimization method to consider a finite rotational temperature is also presented.