Robert J Levis

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We used strong-field laser pulses that were tailored with closed-loop optimal control to govern specified chemical dissociation and reactivity channels in a series of organic molecules. Selective cleavage and rearrangement of chemical bonds having dissociation energies up to approximately 100 kilocalories per mole (about 4 electron volts) are reported for(More)
Quantitative measurements of atenolol, tioconazole, tetraethylammonium bromide, and tetrabutylammonium iodide using laser electrospray mass spectrometry (LEMS) reveal monotonic signal response as a function of concentration for single analytes, two- and four-component equimolar mixtures, and two-component variable molarity mixtures. LEMS analyses of single(More)
Recent advances in nonlinear optics and strong-field chemistry highlight the need for calculated properties of organic molecules and their molecular ions for which no experimental values exist. Both static and frequency-dependent properties are required to understand the optical response of molecules and their ions interacting with laser fields. It is(More)
Laser electrospray mass spectrometry (LEMS) with offline classification is used to discriminate plant tissues at atmospheric pressure using an intense (10(13) W cm(-2)), nonresonant (800 nm) femtosecond laser pulse to vaporize cellular content for subsequent mass analysis. The tissue content of the plant within the 0.05 mm(2) laser interaction region is(More)
Recent investigations of ambient laser-based transfer of molecules into the gas phase for subsequent mass spectral analysis have undergone a renaissance resulting from the separation of vaporization and ionization events. Here, we seek to provide a snapshot of recent femtosecond (fs) duration laser vaporization and nanosecond (ns) duration laser desorption(More)
Nonlinear optics experiments measuring phase shifts induced in a weak probe pulse by a strong pump pulse must account for coherent effects that only occur when the pump and probe pulses are temporally overlapped. It is well known that a weak probe beam experiences a greater phase shift from a strong pump beam than the pump beam induces on itself. The(More)
Simultaneous spatial and temporal focusing pulses are created using parametric pulse shaping and characterized with scanning SEA TADPOLE. Multiple foci are created with optically-controlled longitudal and transverse spatial positions. The characterized foci are in agreement with the predictions of a Fourier optics model. The measurements reveal significant(More)
The low-lying electronic states of O3 and SO2 in their bent and cyclic isomers up to about 10 eV are calculated using the multireference configuration interaction (MRCI) method with a standard Gaussian correlation consistent polarized triple-zeta (cc-pVTZ) basis set. The vertical excitation energies, electron configurations, and oscillator strengths of(More)
The spatio-temporal coupling of shaped laser pulses is measured using scanning SEA TADPOLE as a function of propagation distance through the focal region of a plano-convex lens. A double pulse sequence is measured to have a gradually changing spectral phase across the beam front as a function of propagation distance. When a sinusoidal spectral phase is(More)