AN ATTEMPT TO DETECT INFRARED ABSORPTION IN LIQUID HELIUM

1957 ◽  
Vol 35 (7) ◽  
pp. 818-819 ◽  
Author(s):  
D. C. Baird ◽  
M. H. Edwards ◽  
G. Fleming
Keyword(s):  
Liquid Helium ◽  
Infrared Absorption

Infrared absorption of HCl and HBr in solid nitrogen. Evidence for rotation in a nitrogen matrix

1967 ◽  
Vol 45 (22) ◽  
pp. 2689-2693 ◽  
Author(s):  
K. B. Harvey ◽  
H. F. Shurvell
Keyword(s):  
Liquid Helium ◽  
Infrared Absorption ◽  
Solid Nitrogen

The infrared absorption of HCl and HBr in solid nitrogen at liquid helium temperatures has been recorded. Multiplets have been observed in the region of the fundamental of each molecule. An interpretation is given, based on rotation of the HCl and HBr molecules in the nitrogen matrix.

INFRARED-ABSORPTION SPECTRUM OF ELECTRON BUBBLES IN LIQUID HELIUM

2006 ◽  
Vol 20 (30n31) ◽  
pp. 5291-5300 ◽  
Author(s):  
M. PI ◽  
M. BARRANCO ◽  
V. GRAU ◽  
R. MAYOL
Keyword(s):  
Liquid Helium ◽  
Excited States ◽  
Infrared Absorption ◽  
Density Functional ◽  
Infrared Absorption Spectrum ◽  
Functional Theory ◽  
Electron Bubbles ◽  
Transition Energies ◽  
Solidification Pressure ◽  
Good Agreement

Within finite temperature Density Functional Theory, we have calculated the energy of the transitions from the ground state to the first two excited states in the electron bubbles in liquid helium at pressures from zero to about the solidification pressure. For 4 He at low temperatures, our results are in very good agreement with infrared absorption experiments. We have found that the 1s – 2p transition energies are sensitive not only to the size of the electron bubble, but also to its surface thickness. We also present results for the infrared transitions in the case of liquid 3 He .

A Superconducting Microscope

1971 ◽  
Vol 29 ◽  
pp. 10-11 ◽  
Author(s):  
R. E. Worsham ◽  
J. E. Mann ◽  
E. G. Richardson
Keyword(s):  
Liquid Helium ◽  
Focal Length ◽  
Vacuum System ◽  
Objective Lens ◽  
Electrical Instability ◽  
Radiation Shields ◽  
And Control ◽  
Thermal Oscillations ◽  
Flux Pump

This superconducting microscope, Figure 1, was first operated in May, 1970. The column, which started life as a Siemens Elmiskop I, was modified by removing the objective and intermediate lenses, the specimen chamber, and the complete vacuum system. The large cryostat contains the objective lens and stage. They are attached to the bottom of the 7-liter helium vessel and are surrounded by two vapor-cooled radiation shields.In the initial operational period 5-mm and 2-mm focal length objective lens pole pieces were used giving magnification up to 45000X. Without a stigmator and precision ground pole pieces, a resolution of about 50-100Å was achieved. The boil-off rate of the liquid helium was reduced to 0.2-0.3ℓ/hour after elimination of thermal oscillations in the cryostat. The calculated boil-off was 0.2ℓ/hour. No effect caused by mechanical or electrical instability was found. Both 4.2°K and 1.7-1.9°K operation were routine. Flux pump excitation and control of the lens were quite smooth, simple, and, apparently highly stable. Alignment of the objective lens proved quite awkward, however, with the long-thin epoxy glass posts used for supporting the lens.

Water accumulation as a function of temperature on specimens in an electron microscope cold stage

1986 ◽  
Vol 44 ◽  
pp. 114-115 ◽  
Author(s):  
M.K. Lamvik ◽  
D.A. Kopf ◽  
S.D. Davilla ◽  
J.D. Robertson
Keyword(s):  
Electron Microscope ◽  
Mass Loss ◽  
Liquid Helium ◽  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Liquid Helium Temperature ◽  
Helium Temperature ◽  
Cold Stage ◽  
Water Accumulation ◽  
Better Than

Last year we reported1 that there is a striking reduction in the rate of mass loss when a specimen is observed at liquid helium temperature. It is important to determine whether liquid helium temperature is significantly better than liquid nitrogen temperature. This requires a good understanding of mass loss effects in cold stages around 100K.

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