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Showing 1 to 18 of 18 for “"Supersonic expansion"”.
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Development of a sensitive mid-infrared spectrometer for the study of cooled molecular ions
… spectrometer by the integration of a continuous supersonic expansion discharge source for the production of the cooled molecular ions. Issues with the implementation led to the re- design of the instrument for spectroscopically probing a supersonic expansion discharge directly with NICE-OHMS. …
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Radical-molecule reaction dynamics in the low temperature regime.
… use of the cooling extant in uniform and free supersonic expansions to produce low temperature (90-250 K in the uniform expansion and near 1 K in the free jet) environments which are not at chemical equilibrium. The design of the axisymmetric Laval nozzles, which are integral in producing the …
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Pulsed plasma microjets: a new tool for the investigation of plasma kinetics and molecular spectroscopy
… take place at the rotational level during the expansion process. By integrating a microplasma device with a supersonic nozzle, temperatures as low as 50 K were achieved for molecules having lifetimes shorter than 40 ns and excitation (internal) energies ≳ 11 eV. Additionally, final temperatures …
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Internal and External Vibrations of Weakly Bound Molecular Complexes: Infrared Spectroscopy and Vibrational Analysis
… apparatus. The apparatus features a continuous supersonic expansion source and mass selective detection which employs electron impact ionization and quadrupole mass filtering. A Nd:YAG-pumped optical parametric oscillator (OPO) provided tunable infrared radiation in the 2.5 to 3.5 $\mu$ region.
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Progress in sensitive mid-infrared spectroscopy of cooled molecular ions
… (cm-NICE-OHMS) on a continuous gas-flow pinhole supersonic expansion discharge source for the study of cooled molecular ions. The instrument, which began as a difference-frequency generation (DFG) based system, is upgraded to include a continuous-wave optical parametric oscillator (OPO) easily …
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Development of a quantum cascade laser based spectrometer for high-resolution spectroscopy of gas phase C60
… spectrometer (cw-CRDS) coupled to an oven supersonic expansion source. This is the first such work that uses a QCL in conjunction with the cw-CRD technique and a supersonic expansion source. The primary goal of the research is to acquire a rotationally-resolved, cold, gas-phase spectrum of …
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Development of an Apparatus for the Study of Electron Impact Fragmentation of Molecular Clusters
… molecular clusters is generated using a pulsed supersonic expansion, and this beam is crossed with a pulsed beam of electrons. The electron pulse is 1 μs to provide the necessary time-of-flight resolution. Ionised fragments are detected using a reflectron time-of-flight mass spectrometer with a …
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Supersonic cooling of short-lived molecular states in a pulsed microcavity plasma jet
… pressure and rotationally cooled by supersonic expansion. Spatial-temporal spectrograms of d^3Σ+u→(b^3)π_g (v', v"") = (0, 0) emission are obtained, which contain the information about the dynamic cooling process during the molecular beam expansion. Analysis shows the spatial-temporal …
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High-resolution spectroscopic studies of carbon-containing species
… and either a gas phase or supercritical fluid supersonic expansion source. Future work will focus on optimizing the supercritical fluid source, in addition to setting up a positive column for the study of molecular ions. Astrochemically, rovibrational and rovibronic spectroscopy can allow for …
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Spectroscopic signatures of doorway-mediated intersystem crossing
… population of metastable molecules in a pulsed supersonic expansion is presented and discussed.
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High-resolution infrared spectroscopy of large molecules and water clusters using quantum cascade lasers
… (QCL) based infrared spectrometer coupled to a supersonic expansion source. The spectrometer operates near 8.5 μm and has been developed for the purpose of obtaining a high-resolution gas phase spectrum of C60 for use in astronomical observations of this molecule. Details of the development of …
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Unimolecular decomposition kinetics at resolved internal energies.
… The reacting clusters are formed in a supersonic expansion and bound by the charge-dipole interaction between the organic and the transition metal cation. Rearrangement reactions are initiated by absorption of a visible photon from a dye laser. The most widely used formalism for …
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Electrical properties of silicon surfaces and interfaces
… are fabricated using a pulsed laser ablation supersonic expansion technique. The electrical and electroluminescence characteristics of devices containing these films are shown to be controlled by carrier transport through the nanoparticulate silicon layer. A conduction mechanism encompassing …
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Photodissociation Dynamics of Small Molecules
… of a single 193 nm photon was investigated. Supersonic expansion in a molecular beam was utilized to obtain a narrow distribution of initial parent states. Laser induced fluorescence under collisionless conditions was used in determining the product internal state distributions. It was found …
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SOLVATION OF ORGANIC CATIONS IN THE GAS PHASE AND WITHIN MOLECULAR CLUSTERS
… structures of binary clusters formed by supersonic expansion of mixed vapors. The structures can be identified by comparing the experimentally measured collision cross section values with those predicted from DFT computations.
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Chemical physics and astrochemistry of H3+ and sub Doppler mid infrared spectroscopy of molecular ions
… challenge of ion production. First, a continuous supersonic expansion discharge source is described that allows for the production of internally cold molecular ions in modest abundance, thereby maximizing population in the lowest-lying energy states relevant for astronomical spectroscopy. Then, an …
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Infrared Studies of Intramolecular Rovibrational Relaxation (Kinetics, Energy Transfer)
… molecules are isolated and cooled in a pulsed supersonic expansion. The infrared fluorescence is collected and dispersed using either a cryogenic Michelson interferometer or a circularly variable filter wheel. Resolved fluorescence spectra from dimethyl ether and 1,4 dioxane indicate that the …
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Single-conformation spectroscopy of hydrogen bonding networks: Solvation, synthetic foldamers, and neurodegenerative diseases
<p>The hydrogen bond is one of the most important interactions in natural processes ranging from protein folding to chemical reactions. Two complementary methodologies are applied to understanding this important interaction: top-down and bottom-up. Top-down methods use large molecules, such as …