A liquid-helium cold cell for use with an x-ray diffractometer

Abstract

A l iquid-helium cold cell for u~e lI'i th th e General };lecL l'i c X-ra," gonio nH't,(' 1' ha,; be('n d e,; igll ecl and con,;truetl'd . It is II sed to ob ta in X-ray d iffra c t,io n pHl't.(' I' 11 '; o f pol,\"C ry~t a liin l' ,;olids d (' posi tecl from I'.lll' ga seo Li s phase on a hl'lium-cooll'cI s urface, Thi, 11'01'1, i,; p:lr t of [' he program fo r st udyin g t he stabi li 7,fI,tioll o f fr('(' radi cal s.

Neutron scattering by liquid nitrogen and liquid oxygen

“…Nitrogen and oxygen both have several solid phases [25][26][27][28][29][30][31][32][33][34] and [35][36][37][38][39][40][41][42][43][44][45][46]. Recent X-ray, electron and neutron diffraction experiments have provided information on the structure of these solids which is summarized in table 3.…”

A reexamination of the crystal structures of α and β nitrogen

“…and subsequently annealed at 13 °K. This effect may be due to local overheating during exothermic ordering processes, when the temperatures may momentarily rise above those indicated by the thermocouples (Black et al, 1958). The fl-N~ structure Vegard (1932Vegard ( , 1934 assigned to the centrosymmetric space group P3ml with N atoms in Wyckoff positions 'd' with the molecular centers not coinciding with the space-group symmetry centers.…”

An x-ray diffractometer cryostat providing temperature control in the range 4 to 300°K.

“…B y comparing figure 1 with the corresponding figure in the earlier p aper [1 ] it can b e seen t h at many features of the cryostftt remain un changed. It is ft conventional double D ewar vessel consis ting of a liquid helium vessel (2 1) surrounded by a liquid nitrogen con tain er (22) ftnd mdiaL ion shields (19,3) which screen th e helium vessel from t hermal radia tion.…”

“…\-cr. \-sLalline solid s I'ormcd b~' d eposiLion on ,t surface cooled b y liquid h elium [1] . I It was used with so me SLlccess in stucl :ving lowtemperature solids conden sed hom Lhe gaseous phase, bu t Lite d esign imposed seri o us limitation s 011 t he choice or experim en Lal co nditions.…”