On the Specific Heat of Gases at High Temperatures

Abstract

T HE specific heat of gases at constant pressure was first successfully determined by Regnault. 2 His observations covered the temperature interval from-30 0 to-f 210 0 C. and pressures from 1 to 12 atmospheres. He found that the specific heats of the simple gases, air, oxygen and hydrogen were independent both of temperature and pressure within the limits of the observations. The specific heat of carbon dioxide, on the other hand, when measured between o° and 200 0 showed a well marked increase with increasing temperature. E. Wiedemann, 3 who repeated the experiments of Regnault on a smaller scale, arrived at similar conclusions. Witkowski, 4 investigating air at low temperatures, between ioo° and-170 0 , also found the specific heat constant. On the other hand he found that it increased with increasing pressure (up to 70 atmospheres) and that this increase rose with decreasing temperature. An increase of specific heat with increasing pressure has also been observed by Lussana 5 between o° and 200 0 in the case of air, oxygen and carbon dioxide.

Sputtering in a glow discharge for spectrochemical analysis

“…In a general way, the linear relationship between the reduced sputtering rate and the voltage fits in with the trends reported in the early papers on sputtering in a glow discharge (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29). In view of the above mentioned qualitative character of most of the older data, it is useless to make extensive comparisons.…”

“…(From: F. M. Penning, "Electrical Discharge in Gases," p 41 (Philips' Technical Library, Eindhoven, 1957) When the Grimm glow discharge is operated under proper conditions (see below), the release of atoms from the sample is governed by cathodic sputtering. Sputtering was first observed by Grove (16) and Plücker (17) at the cathode of a glow discharge and has since been the subject of many studies (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37). Numerous experimental results were obtained with some form of glow discharge (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29).…”

“…Sputtering was first observed by Grove (16) and Plücker (17) at the cathode of a glow discharge and has since been the subject of many studies (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37). Numerous experimental results were obtained with some form of glow discharge (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29). However, most of the older data have a qualitative character owing to inadequate control of the experimental conditions.…”

“…From early work on cathode sputtering in glow discharges (18,19), it appears that the mass sputtered in unit time is proportional to the factor (Vc -Vo), where Vc is the abnormal cathode fall and V0 a constant which is greater than the value for the normal cathode fall. The mass sputtered seemed to be also proportional to the discharge current.…”