Abstrakt
We evaluate a population of ortho nuclear spin states in H2 gas in the 22-pole linear radio-frequency trap using N+ ions as a chemical probe. The rate coefficient of the reaction N+ + H2 -> NH+ + H strongly depends on the nuclear spin states of the H2 molecules at the temperature 11 K.
To achieve astrophysically relevant conditions in other our experiments, we convert the normal H2 gas (25% of the molecules in para-states) to H2 gas with a distribution of the nuclear spin states corresponding to the temperatures in prestellar cores (> 99 % in para-states at temperatures 20 K) by a catalytic converter (para-hydrogen generator). Tests by the aforementioned probing reaction show that the abundance of ortho-H2 in such H2 gas is (0:5 0:2)% in the trap.
Para-to-ortho back-conversion of H2 gas in the generator's outlet tube was studied and its rate was estimated to lie in the interval (10-4; 10-2)s-1.