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Featured Research:
View online: https://jcp.aip.org/resource/1/jcpsa6/v138/i17/p174310_s1?isAuthorized=no&ver=pdfcov
Spectroscopic observation of gold-dicarbide: Photodetachment and velocity map imaging of the AuC2 anion

Photoelectron spectra following photodetachment of the gold dicarbide anion, AuC−
2 , have been recorded using the velocity map imaging technique at several excitation wavelengths. The binding energy spectra show well-defined vibrational structure which, with the aid of computational calculations and Franck-Condon simulations, was assigned to a progression in the Au–C stretching mode, ν3. The experimental data indicate that the features in the spectrum correspond to a 2A←3A transition, involving states which we calculate to have bond angles ∼147◦ but with a low barrier to linearity.

EXPERIMENTAL METHOD
Since the specific apparatus used for these experiments has not been previously published, a detailed description is given here. Experiments were performed under high vacuum conditions within a two chamber, differentially pumped system operated at pressures of 1 × 10^−4 and 1 × 10^−6 mbar, respectively. Gold-carbide clusters were produced within a Smalley-type laser ablation source modelled on our existing designs. The source was operated with benzene seeded in helium gas to produce the metal-carbon products. The clusters exit the source and expand towards a two stage Wiley-
McLaren type time of flight where anion species are pulse extracted orthogonally into a drift region. Ion optics corrects the flight path of the extracted anions so that they enter the VMI electrodes positioned immediately after the drift region. The geometry of the time of flight electrodes was designed such that the second order space focus was coincident with the photodetachment point within the VMI electrodes.25 At this point, the ion packets of the clusters were condensed to small volumes and separated in time according to their mass to charge ratio, m/e. Individual m/e species are probed by varying the photodetachment timing. A removable (via a linear motion feed-through), dual micro-channel plate detector (MCP, Del Mar Ventures, Del Mar Photonics MCP-MA25/2) is located immediately after the VMI electrodes to provide mass spectral identification
of cluster species for photodetachment. The velocity map imaging electrodes were pulsed to highvoltage 200 ns prior to the photodetachment event to ensure
stable potentials. Photodetachment was performed via laser light produced by a dye laser pumped by the second harmonic of a Nd:YAG laser. The incident laser power was varied in order to keep the number of detected electrons at a rate of ∼1 per laser pulse, but was typically on the order of a few microjoules at the point of entry into the chamber. To prevent deflection of the photodetached electrons by stray magnetic fields, the detection chamber was lined with magnetic shielding (Co-Netic 0.36 mm thickness, Magnetic Shield Corp.).

Research interests lay in the fields of laser chemistry and reaction dynamics, and include the following themes:

Reaction Dynamics:

Energy partitioning during photodissociation of van der Waals molecules.
Evaporation dynamics at the liquid-vacuum interface.
Electronic Spectroscopy:
Structure of van der Waals clusters.
2-Dimensional Laser Induced Fluorescence (2D-LIF) spectroscopy.
Rovibronic analysis of large polyatomic molecules.
Nanotechnology:
Nanoparticle formation using laser based methods.
Molecular spectroscopy
Reaction dynamics

https://www.dmphotonics.com/MCP_MCPImageIntensifiers/mcpma252.htm

photodetachment cross section
photodetachment spectroscopy
photodetachment of electrons

The engineers at H2W have developed our most compact voice coil positioning stage to date. The customer for this stage requested that it fit within a volume of 1.6 cubic inches (40 cubic mm) cube volume. The application required an ultra-compact stage due to space restrictions in their auto-focus mechanism.

The voice coil positioning stage (VCS02-001-CR-01-MC) is a closed loop system that can be used for high speed positioning and auto-focusing applications. The stage is driven by a NCC type actuator (NCC02-07-001-1R) and is guided by a precision linear crossed roller bearing. The voice coil has a 0.20″ [5.1 mm] stroke; generates 0.26 lbs [1.16 N] of continuous force and 0.78 lbs [3.50 N] of peak force. It includes a 1 micron resolution magnetic linear encoder. Voice coil positioning stages are ideal for applications that require quick, short moves with fast settling times.

Features:
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H2W Technologies is dedicated to the design and manufacture of linear and rotary motion products that are used in the motion control industry. The complete line of linear electric motors includes: single and dual axis linear steppers, DC brush and brushless linear motors, voice coil actuators, and AC induction motors. Also offered is a complete line of ball screw, lead screw and belt driven positioning stages.

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With over 85 years combined experience in the linear and rotary motion field, the H2W Technologies team of engineers offers the optimal solution to the most demanding motion control requirements.

For additional information please contact H2W Technologies, 26380 Ferry Court, Santa Clarita, CA 91350; Tel: (661) 291-1620, Fax: (661) 291-1626, E-Mail: info@h2wtech.com or visit the website at www.h2wtech.com.