Supersonic Molecular Beam
Supersonic Molecular Beam - Related Videos
09:53
Molecular Beam Mass Spectrometry With Tunable Vacuum Ultraviolet (VUV) Synchrotron Radiation
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Cited by 7 •
2012
A molecular beam coupled to tunable vacuum ultraviolet photoionization mass spectrometer at a synchrotron provides a convenient tool to explore the electronic structure of isolated gas phase molecules and clusters. Proton transfer mechanisms in DNA base dimers were elucidated with this technique.
07:34
Schlieren Imaging: A Technique to Visualize Supersonic Flow Features
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2023
Source: Jose Roberto Moreto, Jaime Dorado, and Xiaofeng Liu, Department of Aerospace Engineering, San Diego State University, San Diego, CA Military jet fighters and projectiles can fly at incredible speeds that exceed the speed of sound, which means they are traveling at a supersonic speed. The speed of sound is the speed at which a sound wave propagates through a medium, which is 343 m/s. Mach numbers are used to gauge the flight speed of an object relative to the speed of sound. An object...
10:37
Spatial Separation of Molecular Conformers and Clusters
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Cited by 3 •
2014
We present a technique that allows the spatial separation of different conformers or clusters present in a molecular beam. An electrostatic deflector is used to separate species by their mass-to-dipole moment ratio, leading to the production of gas-phase ensembles of a single conformer or cluster stoichiometry.
08:12
Surface Dye Flow Visualization: A Qualitative Method to Observe Streakline Patterns in Supersonic Flow
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2023
Flow visualization around or on a body is an important tool in aerodynamics research. It provides a method to qualitatively and quantitatively study flow structure, and it also helps researchers theorize and verify fluid flow behavior. Flow visualization can be divided into two categories: off-the-surface visualization and surface flow visualization. Off-the-surface flow visualization techniques involve determining the flow characteristics around the body of interest. They include but are not...
10:31
Plasma-assisted Molecular Beam Epitaxy of N-polar InAlN-barrier High-electron-mobility Transistors
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Cited by 2 •
2016
Molecular beam epitaxy is used to grow N-polar InAlN-barrier high-electron-mobility transistors (HEMTs). Control of the wafer preparation, layer growth conditions and epitaxial structure results in smooth, compositionally homogeneous InAlN layers and HEMTs with mobility as high as 1,750 cm2/V∙sec.
FAQs
Rapid adiabatic expansion through a small nozzle allows the gas to expand quickly without exchanging significant heat with its surroundings. The resulting redistribution of energy shifts thermal energy into forward translational motion. This produces a directed stream whose molecular motion is more uniform, making measurements of collisions, transport, and gas-surface interactions more controlled.
During expansion, intermolecular collisions couple molecules to the rapidly moving gas flow. They convert part of the molecules’ thermal energy into forward translational motion rather than leaving energy distributed across random motion. This collisional stage is central to producing a narrow, directed beam and lowering the rotational and vibrational temperatures relevant to molecular measurements.
Vacuum provides the controlled environment in which the expanding gas can form and travel as a beam. It supports rapid expansion from the pressurized source through the nozzle and helps preserve a directed stream for subsequent measurements. For engineering studies, this control limits uncontrolled influences when examining molecular motion, collisions, or gas-surface interactions.
They create conditions with less internal thermal excitation, supporting high-resolution spectroscopy and reaction dynamics studies. Combined with the beam’s narrow directionality, this control helps isolate molecular motion and collisions. It also assists characterization of gas-surface interactions and molecular transport, both of which are important when engineers study controlled molecular behavior.
A practical sequence begins with pressurized gas, directs it through a small nozzle, and allows rapid adiabatic expansion into vacuum. Intermolecular collisions during expansion redistribute energy toward forward translational motion. The resulting narrow stream can then be directed toward a measurement or target relevant to spectroscopy, surface scattering, reaction dynamics, or deposition studies.
High-resolution spectroscopy benefits from reduced rotational and vibrational temperatures, while surface-scattering studies use the directed stream to examine molecular interactions with surfaces. Reaction-dynamics research can investigate molecular collisions under controlled conditions, and deposition studies can use the beam to study the delivery of gas-phase molecules. Together, these applications connect molecular behavior with measurable engineering outcomes.
Its narrow, directed flow and reduced rotational and vibrational temperatures provide a controlled molecular environment for examining transport and interactions at surfaces. That makes the technique relevant to deposition studies and nanoscale manufacturing, where engineers need to characterize how gas-phase molecules reach and interact with a surface. The same conditions support analysis of gas-surface behavior.