High Precision Measurements of Carbon Disulfide Negative Ion Mobility and Diffusion

TL;DR

This study provides high-precision measurements of negative ion mobility and diffusion in CS2 and a CS2-CF4 mixture, revealing detailed transport properties relevant for gas detector applications.

Contribution

The paper reports the first high-precision measurements of negative ion mobility and diffusion in CS2 and its mixture with CF4, including temperature and capture distance data.

Findings

Reduced mobility in CS2 is 353.0 +/- 0.5 cm^2 Torr / s V.

Mobility in CS2-CF4 mixture is 397.4 +/- 0.7 cm^2 Torr / s V.

Lateral diffusion temperatures are consistent with room temperature.

Abstract

High precision measurements were made of reduced mobility, lateral and longitudinal diffusion of CS2- negative ions in 40 Torr CS2 and a 30 - 10 Torr CS2 - CF4 gas mixture. The reduced mobility was found to be 353.0 +/- 0.5 cm^2 Torr / s V in CS2 and 397.4 +/- 0.7 cm^2 Torr / s V in the CS2 - CF4 gas mixture at STP. The lateral diffusion temperatures for these two gases (295 +/- 15 K and 297 +/- 6 K) were found to be in good agreement with room temperature. By contrast longitudinal diffusion temperature was found to be slightly elevated (319 +/- 10 (stat) +/- 8 (sys) K and 310 +/- 20 (stat) +/- 6 (sys) K) though given the errors, room temperature diffusion can not be ruled out. For lateral diffusion significant capture distances (0.21 +/- 0.07 mm and 0.15 +/- 0.03 mm) were measured while for longitudinal diffusion the results were not conclusive.