Pd. Mixon et al., PULSE OPTIMIZATION CRITERIA FOR THE MICROCAVITY HOLLOW-CATHODE DISCHARGE EMISSION SOURCE, Journal of analytical atomic spectrometry, 9(6), 1994, pp. 697-700
Criteria are presented that are important for optimizing the emission
intensity in a microcavity hollow cathode (MCHC) discharge source oper
ated in the pulsed mode. The d.c. component must be sufficiently large
to ensure a continuous discharge inside the HC. It is shown that the
pulse parameters that result in maximum light output for the spectral
lines of the cathode material do not result in maximum light output fr
om sodium as an analytical sample which has been mounted inside the HC
. This lack of correlation may be due to either the physical and chemi
cal properties of the species or to the manner in which the species en
ters the HC discharge plasma. Voltage-current characteristics are pres
ented for the MCHC to illustrate the role of the d.c. component during
pulsed mode operation. The d.c. current of the discharge must be >5 m
A in order to maintain a discharge in the HC. At currents <5 mA for th
is system the discharge is restricted to the planar surface of the cat
hode and will not participate in the excitation of analytes thrown int
o the hollow space during the pulse.