State-to-state scattering of highly vibrationally excited NO with argon at collision energies over 1 eV.

We present state-to-state differential cross sections for rotationally inelastic collisions of vibrationally excited NO XΠ ( = 9) with Ar using a near-counterpropagating molecular beam geometry. These were obtained using the stimulated emission pumping technique coupled with velocity map imaging. Collision energies well over ∼1 eV were achieved and rotational excitations up to ∼Δ = 60 recorded for the first time for inelastic collisions.

State-to-State Spin-Orbit Changing Collision Dynamics of Vibrationally Excited NO at Collision Energies from 1.4 eV to the Cold Regime.

State-to-state spin-orbit changing collisions of vibrationally excited nitric oxide (NO) with argon (Ar) were studied across a wide collision energy range from 3.5 to 11,200 cm (0.43 meV to 1.

Cold collisions of hot molecules.

In this Perspective, we review our recent work on rotationally inelastic collisions of highly vibrationally excited NO molecules prepared in single rotational and parity levels at = 10 using stimulated emission pumping (SEP). This state preparation is employed in a recently developed crossed molecular beam apparatus where two nearly copropagating molecular beams achieve an intersection angle of 4° at the interaction region. This near-copropagating beam geometry of the molecular beams permits very wide tuning of the collision energy, from far above room temperature down to 2 K where we test the theoretical treatment of the attractive part of the potentials and the difference potential for the first time.

Differential Cross Sections for Cold, State-to-State Spin-Orbit Changing Collisions of NO( = 10) with Neon.

Inelastic scattering processes have proven a powerful means of investigating molecular interactions, and much current effort is focused on the cold and ultracold regime where quantum phenomena are clearly manifested. Studies of collisions of the open shell nitric oxide (NO) molecule have been central in this effort since the pioneering work of Houston and co-workers in the early 1990s. State-to-state scattering of vibrationally excited molecules in the cold regime introduces challenges that test the suitability of current theoretical methods for determination of intermolecular potentials, and concomitant electronically nonadiabatic processes raise the bar further.

A versatile molecular beam apparatus for cold/ultracold collisions.

We have developed an apparatus capable of performing intrabeam and near-copropagating beam scattering experiments at collision energies from room temperature to below 1 K where interesting quantum phenomena can be observed. A detailed description of the major components of the apparatus, single and dual molecular beam valves, high speed chopper, and the discharge source, is presented. With the intrabeam scattering setup, a novel dual-slit chopper permits collision energies down to millikelvins with a collision energy spread of 20%.

State-to-state scattering of highly vibrationally excited NO at broadly tunable energies.

Experimental developments continue to challenge the theoretical description of molecular interactions. One key arena in which these advances have taken place is in rotationally inelastic scattering. Electric fields have been used with great success to select the initial quantum state and slow molecules for scattering studies, revealing novel stereodynamics, diffraction oscillations and scattering resonances.

Differential Cross Sections for State-to-State Collisions of NO( v = 10) in Near-Copropagating Beams.

State-to-state differential cross sections for rotationally inelastic collisions of vibrationally excited NO with Ar have been measured in a near-copropagating crossed beam experiment at collision energies of 530 and 30 cm. Stimulated emission pumping (SEP) to prepare NO in specific rovibrational levels is coupled with direct-current slice velocity map imaging to obtain a direct measurement of the differential cross sections. The use of nearly copropagating beams to achieve low NO-Ar collision energies and broad collision energy tuning capability are also demonstrated.