Spectroscopic characterization of the metastable 3pπ 3Π+,0− valence states and the 4s3Σ+ Rydberg states of the MgKr and MgXe van der Waals molecules

Abstract

The first metastable valence excited states and the first Rydberg states of the MgKr and MgXe molecules have been characterized by resonance two-photon photoionization (R2PI) spectroscopy. The Mg(3s3p 3PJ)⋅RG(3Π0+,0−) metastable states, produced by expanding the products of a laser-ablated magnesium rod in Kr/Ar or Xe/Ar gas mixtures into a supersonic expansion, were excited by a dye laser pulse to several vibrational levels of the Mg(3s4s 3S1)⋅RG(3Σ+) Rydberg states, with detection by ionization with a second dye laser pulse. Spectroscopic constants, bond energies, and bond lengths are reported for both states of MgKr and MgXe. The 3Σ+ Rydberg states are much more strongly bound than the lower 3Π0− valence states, and in fact are essentially as strongly bound as the ground states of the analogous MgRG+ ions, characterized previously in the same apparatus. This clearly indicates that the RG atoms can readily penetrate the diffuse Mg(4s) Rydberg electron cloud. The interesting and unusual spin–orbit and “spin–spin” effects observed are attributed to mixing of some RG character into wave functions of predominantly Mg* excited state character. Bonding and spin–orbit interactions in the MgAr, MgKr, and MgXe first triplet metastable and Rydberg states are discussed.

Theoretical Study of M+−RG and M2+−RG Complexes and Transport of M+ through RG (M = Be and Mg, RG = He−Rn)

“…The R 0 value was determined to be 3.17 ( 0.05 Å, which is in very good agreement with the present value of 3.192 Å. The only other theoretical values appear to be those of Leung et al 29 who reported QCISD(T) valuesssee Table 1; the agreement with the present values for R e , D e , and ω e is generally good, although a The quantities refer to the following isotopes: 24 Mg, 4 He, 20 Ne, 40 In a similar way to that discussed above for Be + -Ar, consideration of near-dissociation behavior of vibrational energy spacings has led Le Roy 25 to derive improved estimates of D 0 values, including error ranges, for Mg + -Ar, Mg + -Kr, and Mg + -Xe, using the excited state vibrational information from Pilgrim et al 21 Ground state values could then be derived from these values as: 1210 ( 165 cm -1 for Mg + -Ar; 1812 ( 591 cm -1 for Mg + -Kr; and 3299 ( 1654 cm -1 for Mg + -Xe. These values are consistent with the present calculated values, and with those of ref 21 within the large error ranges derived in ref 25.…”

“…The rovibrational energy levels for each potential energy curve were obtained using the LEVEL 44 program, and the few lowest calculated energy levels were least-squares fitted to standard expressions to obtain the reported spectroscopic quantities. The most abundant naturally occurring isotope of each element was used in all cases ( 9 Be, 24 Mg, 4 He, 20 Ne, 40 Ar, 84 Kr, 132 Xe, and 222 Rn).…”

Interactions of C + ( 2 P J ) with rare gas atoms: incipient chemical interactions, potentials and transport coefficients

“…It is interesting that, for C + -Kr and C + -Xe, there are more marked differences between the values of the spectroscopic parameters for the 2 Π term, and both the 2 Π 1/2 and 2 Π 3/2 levels. We have noted above that the 2 Π 1/2 -2 Π 3/2 splittings are significantly above even Hund's case (c) splitting for the heaviest two species and this suggests that other factors have come into play-this is again evidence for the mixing in of C-RG + character discussed above, where the We note that this involvement of the RG orbitals has been observed in the excited states of M + -RG complexes ( [38] and references therein), and this has been considered by both Duncan and co-workers [39] and Breckenridge and co-workers [40] in their electronic spectroscopic study of Mg + -RG complexes.…”

Hybridization and Covalency in the Group 2 and Group 12 Metal Cation/Rare Gas Complexes

“…A summary of the derived spectroscopic constants obtained from the IECs are provided in Table 1 for the Group 2 complexes, and Table 2 for the Group 12 complexes. The key experimental data 33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52 are displayed in Tables 1 and 2, as well as comparisons between the present and our previous work. Since these complexes have been previously studied using subsets of the approaches taken here, and in those studies generally very good agreement between previous theoretical and experimental work was seen, 6,7,8,9,12,13 a full survey of previous experimental and theoretical studies is not repeated herein.…”