相关论文: A pulsed, low-temperature beam of supersonically c…
A special class of molecules that are important to many subfields in molecular dynamics and chemical physics, namely free radical molecules, now enjoy a significant degree of center-of-mass motion control in the laboratory frame. The…
We demonstrate a new gas-based OH generation source using a low power RF-driven atmospheric pressure plasma configured to deliver the radical flux into the far effluent region, well away from interference from other plasma factors such as…
We report bunching, slowing, and acceleration of a supersonically cooled beam of diatomic hydroxyl radicals (OH). \textit{In situ} observation of laser-induced fluorescence along the beam propagation path allows for detailed…
We describe a pulsed rotating supersonic beam source, evolved from an ancestral device [M. Gupta and D. Herschbach, J. Phys. Chem. A 105, 1626 (2001)]. The beam emerges from a nozzle near the tip of a hollow rotor which can be spun at…
Atomic physics was revolutionized by the development of forced evaporative cooling: it led directly to the observation of Bose-Einstein condensation, quantum-degenerate Fermi gases, and ultracold optical lattice simulations of condensed…
A recent expansion of cold and ultracold molecule applications has led to renewed focus on molecular species preparation under ultrahigh vacuum conditions. Meanwhile, molecular beams have been used to study gas phase chemical reactions for…
Metastable helium molecules (He$_2^*$) have been generated by striking a discharge in a supersonic expansion of helium gas from a pulsed valve. When operating the pulsed valve at room temperature, 77K, and 10K, the mean velocity of the…
Atmospheric pressure steam/oxygen plasma is generated by a 88 Hz, 6kV AC power supply. The properties of the produced plasma are investigated by optical emission spectroscopy (OES). The relative intensity, rotational, vibrational,…
We introduce a general technique to generate compressed broadband terahertz pulses based on difference frequency generation of optical pump radiation using aperiodically poled structures. The pump pulse format and poling of the crystals…
Stimulated emission of radiation has not been directly observed in astrophysical situations up to this time. Here we demonstrate that photons from pulsar B1641-45 stimulate pulses of excess 1720 MHz line emission in an interstellar OH…
Intense beams of cold and slow molecules are produced by supersonic expansion out of a rapidly rotating nozzle, as first demonstrated by Gupta and Herschbach. An improved setup is presented that allows to accelerate or decelerate cold…
A novel method is presented for generating radiation using the beat wave associated with a bi-frequency laser pulse, to excite plasma oscillations in a plasma slab with a density gradient. By resonantly exciting a plasma wave, it can be…
We studied the effects of cryogenic cooling of a 2-[3-(4-hydroxystyryl)-5, 5-dimethylcyclohex-2-enylidene] malononitrile (OH1) crystal on the generation of broadband THz pulses via collinear optical rectification of 1350 nm femtosecond…
Ultrashort laser pulses are widely used for transient field-free molecular orientation -- a phenomenon important in chemical reaction dynamics, ultrafast molecular imaging, high harmonics generation, and attosecond science. However,…
X-ray beams carrying orbital angular momentum (OAM), are emerging as a powerful tool to probe matter. Recently, a method called self-seeded FEL with OAM (SSOAM) has been proposed to generate high-power x-ray OAM pulses, which places the…
A pulsed cooling scheme for optomechanical systems is presented that is capable of cooling at much faster rates, shorter overall cooling times, and for a wider set of experimental scenarios than is possible by conventional methods. The…
Barium monohydride (BaH) is an attractive candidate for extending laser cooling and trapping techniques to diatomic hydrides. The apparatus and high-resolution optical spectroscopy presented here demonstrate progress toward this goal. A…
We demonstrate a technique for producing a cold pulsed beam of atoms by transferring a cloud of atoms trapped in a three dimensional magneto-optic trap (MOT). The MOT is loaded by heating a getter source of Rb atoms. We show that it is…
The double-resonant laser excitation of nitric oxide, cooled to 1 K in a seeded supersonic molecular beam, yields a gas of $\approx10^{12}$ molecules cm$^{-3}$ in a single selected Ryberg state. This population evolves to produce prompt…
Ultrashort electron pulses with a high average current provide a powerful means of enhancing time-resolved imaging and photon generation. In this study, we report the attosecond shaping of sub-relativistic electron beams using membranes in…