13–30 micron diameter microdischarge devices: Atomic ion and molecular emission at above atmospheric pressures

Abstract

Cylindrical microdischarge devices having cavity diameters as small as 13 μm and volumes as low as several nanoliters have been fabricated in metal/polymer structures with and without screen electrodes. These devices produce stable glow discharges in Ne, Xe, air, ${\mathrm{Xe/O}}_2,$ and Ne/air mixtures at total pressures up to the maximum investigated, 1200 Torr. Neon discharges in 30 μm diameter devices are well behaved for $p_{\mathrm{Ne}}$ above 700 Torr $\text{(pd>2.1}$ Torr cm) and generate strong emission in the UV from singly charged Ne-ion transitions at above-atmospheric pressures. Fluorescence in the visible from ${\mathrm{Xe}}^{+}$ and ${\mathrm{Xe}}^{\text{2+}}$ as well as molecular features in the green (∼530 nm) and blue (∼484 nm) that appear to be attributable to the neutral dimer are also observed from Xe in the 650–1100 Torr range. Discharges in air (100–740 Torr) and Ne/air mixtures produce strong ${\mathrm{N}}_2\mathrm{(C\to B)}$ and ${\mathrm{N}}_2^{+}\mathrm{(B\to X)}$ emission in the near-UV and violet. The lowest observed operating voltage for Ne discharges in 30 μm devices is 87 V ${\mathrm{(p}}_{\mathrm{Ne}}\text{=1200}$ Torr). Discharges in microcavities of dimensions below 50 μm represent a unique spectroscopic tool.