Binary and ternary recombination of ${\rm D}_3^+$D3+ ions at 80–130 K: Application of laser absorption spectroscopy

Abstract

Recombination of D(3)(+) ions with electrons at low temperatures (80-130 K) was studied using spectroscopic determination of D(3)(+) ions density in afterglow plasmas. The use of cavity ring-down absorption spectroscopy enabled an in situ determination of the abundances of the ions in plasma and the translational and the rotational temperatures of the recombining ions. Two near infrared transitions at (5792.70 ± 0.01) cm(-1) and at (5793.90 ± 0.01) cm(-1) were used to probe the number densities of the lowest ortho state and of one higher lying rotational state of the vibrational ground state of D(3)(+) ion. The results show that D(3)(+) recombination with electrons consists of the binary and the third-body (helium) assisted process. The obtained binary recombination rate coefficients are in agreement with a recent theoretical prediction for electron-ion plasma in thermodynamic equilibrium with α(bin)(80 K) = (9.2 ± 2.0) × 10(-8) cm(3) s(-1). The measured helium assisted ternary rate coefficients K(He) are in agreement with our previously measured flowing afterglow data giving a value of K(He)(80 K) = (1.2 ± 0.3) × 10(-25) cm(6) s(-1).

Binary Recombination of H3+ and D3+ Ions with Electrons in Plasma at 50–230 K

“…As in the case of H 3 + , the results obtained for D 3 + are in good agreement with theoretical calculations and with other experiments. No substantial difference between present values and values obtained in SA-CRDS experiment conducted at order of magnitude higher n e was observed. As in the case of H 3 + dominated plasma we have seen no substantial influence of E-CRR on the overall recombination of D 3 + ions with electrons over the range of experimental conditions.…”

“…Together with binary recombination rate coefficients α bin we also evaluated the ternary recombination rate coefficients K He for the recombination of H 3 + and D 3 + ions with electrons in the temperature range 50–230 K. These results are published elsewhere together with a thorough discussion of possible ternary recombination processes occurring in low temperature plasmas. The temperature range 80–300 K was already covered in our previous experiments; ,,, the present data were measured over wider temperature and pressure ranges than in the FALP , experiments and with better accuracy and temperature stability. The agreement with these previous studies is good.…”

“…We measured the dependence of the effective recombination rate coefficient on the D 2 number density at particular temperatures and pressures and obtained the binary α bin and the ternary K He recombination rate coefficients for the recombination of D 3 + ions with electrons. The measured binary recombination rate coefficients of recombination of D 3 + ions with electrons are plotted in Figure together with values from previous SA-CRDS, FALP, and CRYRING experiments. The theoretical dependences calculated by Kokoouline and by Pratt and Jungen are also plotted in Figure .…”

“…Full circles indicate the present data obtained in the Cryo-FALP II experiment. Open rhomboids are the values obtained in SA-CRDS experiment . Open circles are data from previous FALP experiments.…”

“…The recombination of D 3 + ions with electrons was also studied in storage ring experiments and in plasmatic experiments. ,, Up to now there is only one study in a D 3 + dominated plasma with spectroscopically resolved recombining ions . In that experiment the measured kinetic and rotational temperatures of the recombining ions was also close to the buffer gas temperature (for details see ref ).…”