SPECTROSCOPY OF METASTABLE $N(^{2}D)$ AND $Ne(^{3}P_{2})$ ATOMS ISOLATED BY SOLID HELIUM

Abstract

The discovery of the Impurity-Helium Solid Phase $(IHSP)^{1}$ allows to achieve a reliable long-time isolation of metastable species by helium. The long-lived nitrogen $N(^{2}D)$ atoms seem to be a persuading spectroscopic object here. They turn out to survive more than $10^{4}$ s in IHSP with radiative decay caused solely by a heavy particle (nitrogen molecule or rare gas atom) $neighborhood^{2}$. The comparison of atomic $N(^{2}D \to {^{4}}S)$ at $\lambda \approx 520$ nm and atom-molecular vibronic $N(^{2}D) - N_{2}(/nu=0) \to N(^{4}S) - N_{2}(/nu=1)$ at $ \lambda \approx 595$ nm luminescences have confirmed that the molecular-like spectra shapes are consequense of the excimer state formation. The excimer-like nature of isolated $N(^{2}D)$- Rg pairs $(Rg \equiv Ne, Ar, Kr, Xe)$ is evidenced by their both spectra shapes and luminescence lifetimes observed. Thermoluminescence studies give the energy barrier for two isolated in IHSP neighboring heavy particles fusion, $E_{act} = 40 \pm 4 K^{2}$. In contrast LIF study of the isolated in IHSP solitary $Ne(^{3}P_{2})$ atoms has shown the lines nonbroadened and nonshifted with experimental accuracy of $0.06 {\AA}$, in spite $Ne(^{3}P)$ atom is close analog of alkali ones for which large spectra disturbance by both liquid and solid helium have been elucidated.