Luminescence spectroscopy of matrix-isolated atomic cadmium

Electronic spectroscopy of ytterbium in a neon matrix

The low-lying electronic states of Yb isolated in a solid Ne matrix are characterized through absorption and emission spectroscopy. The absorption spectra of matrix isolated Yb while pumped into its triplet states have been recorded for the first time and the 6s6p (3)P(J) → 5d6s (3)D(1, 2) transition frequencies obtained. Under matrix conditions, the structure of these states is found to be qualitatively the same as in the free atom, but the intersystem crossing rate is observed to be several orders of magnitude greater. A proposed explanation for this is curve crossings between the bound potential energy surface correlated to the 6s6p (1)P(1) state and the potential energy surfaces correlated to the 5d6s (3)D(1, 2) states in isolation. The potentials of the Yb·Ne dimer in its lowest electronic states are computed ab initio and used in a pairwise cluster model to explicitly demonstrate these curve crossings.

Luminescence spectroscopy of matrix-isolated zP6 state atomic manganese

The relaxation of electronically excited atomic manganese isolated in solid rare gas matrices is observed from recorded emission spectra, to be strongly site specific. z 6P state excitation of Mn atoms isolated in the red absorption site in Ar and Kr produces narrow a 4D and a 6D state emissions while blue-site excitation produces z 6P state fluorescence and broadened a 4D and a 6D emissions. MnXe exhibits only a single thermally stable site whose emission at 620 nm is similar to the broad a 6D bands produced with blue-site excitation in Ar and Kr. Thus in Ar(Kr), excitation of the red site at 393 (400) nm produces narrow line emissions at 427.5 (427.8) and 590 (585.7) nm. From their spectral positions, linewidths, and long decay times, these emission bands are assigned to the a 4D72 and a 6D92 states, respectively. Excitation of the blue site at 380 (385.5) nm produces broad emission at 413 (416) nm which, because of its nanosecond radiative lifetime, is assigned to resonance z 6P --> a 6S fluorescence. Emission bands at 438 (440) and 625 (626.8) nm, also produced with blue-site excitation, are broader than their red-site equivalents at 427.5 and 590 nm (427.8 and 585.7 nm in Kr) but from their millisecond and microsecond decay times are assigned to the a 4D and a 6D states. The line features observed in high resolution scans of the red-site emission at 427.5 and 427.8 nm in MnAr and MnKr, respectively, have been analyzed with the W(p) optical line shape function and identified as resolved phonon structure originating from very weak (S=0.4) electron-phonon coupling. The presence of considerable hot-phonon emission (even in 12 K spectra) and the existence of crystal field splittings of 35 and 45 cm(-1) on the excited a 4D72 level in Ar and Kr matrices have been identified in W(p) line shape fits. The measured matrix lifetimes for the narrow red-site a 6D state emissions (0.29 and 0.65 ms) in Ar and Kr are much shorter than the calculated (3 s) gas phase value. With the lifetime of the metastable a 6D92 state shortened by four orders of magnitude in the solid rare gases, it is clear that the probability of the "forbidden" a 6D --> a 6S atomic transition is greatly enhanced in the solid state. A novel feature identified in the present work is the large width and shifted 4D and 6D emissions produced for Mn atoms isolated in the blue sites of Ar and Kr. In contrast, these states produce narrow, unshifted (gas-phase-like) 4D and 6D state emissions from the red site.

The absorption and excitation spectroscopy of matrix-isolated atomic manganese: Sites of isolation in the solid rare gases

This study collects information from absorption and luminescence excitation spectra recorded for Mn atoms isolated in the solid rare gases Ar, Kr, and Xe and presents an analysis of the site occupancy, based on the polarizabilities of the rare gases and the observed spectral shifts. Two thermally stable sites of isolation exist for atomic Mn in solid Ar and Kr, while a single thermally stable site is present in Mn/Xe. Site occupancy assignments are based on the application of a polarizability model to the z (6)P(5/2)<--a (6)S(5/2); z (8)P(5/2)<--a (6)S(5/2), and y (6)P(5/2)<--a (6)S(5/2) electronic transitions of atomic Mn. From an analysis of the observed RG matrix-to-gas phase energy shifts for P<--S type transitions, this model allows the association of certain site types occupied by metal atoms in the rare gas solids. The required condition being a linear dependence of the matrix shifts with rare gas polarizability for those metal atoms "trapped" in a particular site type. Application of the polarizability model in conjunction with trends observed in site dominance, established a connection between the blue sites in Ar and Kr and the single site in Xe. Use of the known MgRG ground state bond lengths facilitated an identification of the sites of Mn atom isolation assuming the transference of the known MgRG bond lengths to the MnRG systems. Substitutional site occupancy of atomic Mn is assigned to the blue sites in Ar and Kr and the single site in Xe, while tetra-vacancy site occupancy is assigned to the red sites in Ar and Kr. Consistent with these assignments, Mn atoms in solid Ar show a preference for trapping in tetra-vacancy sites whereas in solid Kr, single substitutional sites are preferred and in Xe, this is the only site observed.