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The scanning helium microscope (SHeM) is a form of microscopy that uses low-energy (5–100 meV) neutral helium atoms to image the surface of a sample without any damage to the sample caused by the imaging process. Since helium is inert and neutral, it can be used to study delicate and insulating surfaces.
As the helium ion beam interacts with the sample, it does not suffer from a large excitation volume, and hence provides sharp images with a large depth of field on a wide range of materials. Compared to a SEM, the secondary electron yield is quite high, allowing for imaging with currents as low as 1 femtoamp. The detectors provide information ...
An HID connected to a gas chromatograph (GC) has the great advantage to use helium as both the carrier gas and the ionization gas. An HID is an ion detector which uses a radioactive source, typically β-emitters, to create metastable helium species. [1] The radioactive source ionizes helium atoms by bombarding them with emissions.
1-10 minutes, or up to 18 hours Visual disturbance, eye pain, pinpointing of the pupils, runny nose, chest tightness, breathing difficulty, cough, severe nasal congestion, nausea, diarrhea, vomiting, and twitching, VX Gas: colorless Odor: none 1-10 minutes, or up to 42 hours Constricted pupils, visual disturbance, eye pain, runny nose,
A gas pycnometer is a laboratory device used for measuring the density—or, more accurately, the volume—of solids, be they regularly shaped, porous or non-porous, monolithic, powdered, granular or in some way comminuted, employing some method of gas displacement and the volume:pressure relationship known as Boyle's law.
Helium is an important resource for many applications, especially MRI machines, but the gas is hard to come by on planet Earth. While the world has been suffering a helium shortage for more than a ...
Helium is inert - it does not react with other substances or combust - and its atomic number is 2, making it the second lightest element after hydrogen. Rockets need to achieve specific speeds and ...
Bettors like all but one home team in the four NFL wild-card games remaining. Ahead of Sunday’s action, all three home teams are getting the majority of bets and money against the spread at ...