Caddisflies (Trichoptera) of Wildcat Creek, Pickens County, South Carolina

Sixty-two species of caddisflies (Trichoptera) were identified from collections make from Wildcat Creek over a period of 33 years. A new distributional record for South Carolina was obtained for Diplectrona metaqui. Eight species, Polycentropus carlsoni, Wormaldia thyria, Neotrichia collata, Stactobiella delira, Neophylax atlanta, Goera fuscula, Pseudogoera singularis, and Agarodes griseus, are considered to be threatened in South Carolina

Resonant two-photon ionization spectroscopy of jet-cooled Au?

Journal ArticleA band system of jet-cooled Au, has been located in the near infrared region of the spectrum using resonant two-photon ionization spectroscopy. The origin band is located at 13 354.15 cm-? and the system extends more than 700 cm-? further to the blue. The excited state displays a radiative lifetime of approximately 28 ?s, corresponding to an absorption oscillator strength of f~.0003. Accordingly, it is thought that the transition corresponds to a spin-forbidden doublet (S = l/2) to quartet (S = 3/2) transition, which is made allowed by spin-orbit contamination, presumably in the upper state. A progression in a totally symmetric stretching vibration (? = 179.7 cm-?) is obvious in the spectrum, along with a much weaker progression in another mode, which displays an interesting pattern of splittings. Although no assignment is absolutely unambiguous, various candidates are presented. The most likely of these assigns the system as an ? ?E ? ?x ?E? transition in the D?h point group, with both the ground X?E? and excited ? ?E? states undergoing Jahn-Teller distortion. The vibronic levels of the ? ?E? state have been fitted assuming a linear Jahn-Teller effect in a system with both spin-orbit splitting and a significant anharmonicity in the Jahn-Teller active e? vibrational mode. The combined effects of anharmonicity in the Jahn-Teller active mode and spin-orbit coupling appear not to have been previously investigated, they are therefore examined in some detail

Spectroscopic studies of jet-cooled CuAg

Journal ArticleResonant two-photon ionization spectroscopy has been applied to jet-cooled diatomic CuAg. Four band systems have been observed, three of which have been rotationally resolved and analyzed. The ground state is X ??+ in symmetry, deriving from the 3d??cu4d??Ag?? molecular configuration. Its bond length has been determined as ro = 2.3735 ? 0.0006 ? (1? error limits). Based on an analysis of the possible separated atom limits, three of the excited states observed (A0+, A?1, and B?0+) are assigned as primarily 3d?cu4d??Ag???* in character. The observation of unusually large electronic isotope shifts in the A-X, A ?-X, and B ?-X band systems, similar in magnitude to those previously observed in the A-X and B-X systems of Cu?, and the s?d excitations in atomic copper, provides further confirmation that these excited states derive from the 3d?Cu4d??Ag ???* molecular configuration. Finally, the highest energy state observed in this work is argued to be primarily ion pair in character, and is expected to have significant contributions from both the Cu + Ag - and Cu - Ag + ion pair states

Spectroscopy of AlAr and AlKr from 31 000 cm-1 to the ionization limit

Journal ArticleSpectra of jet-cooled AlAr and AlKr have been collected over the range from 31 000 cm -? to the ionization limit, using the technique of resonant two-photon ionization spectroscopy with mass spectrometric detection. Adiabatic ionization potentials have been accurately measured for both molecules, and have been estimated for AlAr? and AlAr?. The spin-orbit splittings in the X ?II ground state have been determined for both AlAr and AlKr, and ground-state bond strengths have been accurately measured as Do [AlAr, Xi ?II1/2 (3p)] = 122.4 ? 4 cm-? and D?[27A1 84Kr, X, ?II1/2 (3p)] = 194.7 ? 0.8 cm-? . These values have also been combined with the measured ionization potentials to derive D?(Al+-Ar) = 982.3 ? 5 cm-? and D?(Al+-Kr) = 1528.5 ? 2cm- ?

Resonant two-photon ionization spectroscopy of coinage metal trimers: Cu?Ag, Cu?Au, and CuAgAu

Journal ArticleThe jet-cooled coinage metal triatomic molecules Cu, Ag, Cu, Au, and CuAgAu have been investigated using resonant two-photon ionization spectroscopy. One band system, labeled as the ?-x system, has been observed for each species, with origin bands at 13 188, 17 217, and 17 470 cm -?, respectively. Vibrational progressions have been assigned and vibrational constants have been extracted using a linear least-squares fitting procedure. For Cu, Ag, 47 vibrational bands have been assigned within the ?-X system. The upper states of these bands derive from combinations of two symmetric (a,) and one antisymmetric (b,) mode in the C?v point group. For the ?-2 system of Cu?Au, only seven vibrational bands have been observed, all occurring within a 500 cm-? range. Lifetime measurements for the observed vibrational levels support the possibility that predissociation may be occurring in the ? excited state of Cu?Au and this may be limiting the number of vibrational levels observed within this state. Finally, in the case of CuAgAu, 92 vibrational bands have been assigned, corresponding to excitations of three totally symmetric (a?) vibrational modes in the Cg point group. For this molecule, a complete set-of vibrational frequencies (?i ) and anharmonicities (xy) have been obtained for the excited ? state. In addition, the observation of weak hot bands in the spectrum permits the three vibrational modes of the X ground state to be characterized by v? = 222.83 ? 0.29, v? = 153.27 ? 0.22, and v? = 103.90 ? 0.28 cm-? for 63Cu?07Ag?97Au (la error limits)

Resonant two-photon ionization spectroscopy of jet-cooled OsN: 520?418 nm

Journal ArticleThe optical transitions of supersonically cooled OsN have been investigated in the range from 19 200 to 23 900 cm?1 using resonant two-photon ionization spectroscopy. More than 20 vibronic bands were observed, 17 of which were rotationally resolved and analyzed. The ground state is confirmed to be 2?5/2, deriving from the 1?2 2?2 1?4 1?3 3?2 electronic configuration. The X 2?5/2 ground state rotational constant for 192Os14N was found to be B0 = 0.491921(34) cm?1, giving r0 = 1.62042(6) ? (1? error limits). The observed bands were grouped into three band systems with ?" = 7/2 and four with ?" = 3/2, corresponding to the three 2?7/2 and four 2?3/2 states expected from the 1?2 2?2 1?4 1?3 3?1 2?1 and 1?2 2?2 1?4 1?2 3?2 2?1 electronic configurations. In addition, two interacting upper states with ?"= 5/2 were observed, one of which is thought to correspond to a 1?2 2?2 1?3 1?3 3?2 2?1, 2?5/2 state. Spectroscopic constants are reported for all of the observed states, and comparisons to related molecules are made. The ionization energy of OsN is estimated as IE(OsN) = 8.80 ? 0.06 eV

Spectrsocopy of Jet-cooled YCu

Journal ArticleOptical spectra of jet-cooled diatomic YCu have been recorded using resonant two-photon ionization spectroscopy in a supersonic expansion of helium. The ground state is shown experimentally to be of 1?+ symmetry, with a measured bond length of re"=2.6197(6) ? and a vibrational frequency of 193.21(24) cm-1 for 89Y63Cu. Five excited electronic states are identified as the [10.2]1?+ state, the [11.8]3IIo+ state, the [12.0]3II, state, the [14.0[I1I state, and, with the help of ab initio theory, the [12.2]1II state. No evidence whatever for participation of the 3d orbitals of copper in the chemical bonding is found, and the electronic structure of YCu is found to exhibit a striking similarity to that of YH

Spectroscopic studies of jet-cooled AgAu and Au?

Journal ArticleResonant two-photon ionization spectroscopy has been applied to the jet-cooled Au? and AgAu molecules. Three new band systems of Au? and two new systems of the poorly characterized AgAu molecule have been observed. Excited state lifetime measurements have been made, and assignments of the excited states are suggested For Au? the a ???u+ X ??g+ transition has been detected, and vibrational levels of the a ???u+ state have been observed up to v? = 33, which lies only 120cm -? below the convergence limit of the system.T his allows a precise confirmation of previous high temperature Knudsen effusion measurements of the bond strength of Au, as D??(Au?) = 2.290 ? 0.008 eV. In addition, the excited states of Au? of 0u+ symmetry are shown to have significantly shorter fluorescence lifetimes than the 1u states, and this is explained as resulting from an admixture of Au + Au- ion pair character in these ?' = 0u+ states. The ionization potential of Au, has been bracketed as IP(Au?) = 9.20 ? 0.2 1 eV, which may be combined with the values of D??(Au?+) and IP(Au) to provide the dissociation energy of the Au: ion as DAu? (Au?+)=2.32 ? 0.2 1 eV. Detailed comparisons with theoretical results are made for Au,, and assignments of the A and B states of AgAu to ?'= 0 + and ?? = 1, respectively, are proposed

Spectroscopy of mixed early-late transition metal diatomics: ScNi, YPd, and ZrCo

Journal ArticleResonant two-photon ionization spectroscopy has been employed to investigate the spectra of the jet-cooled transition metal diatomics ScNi, YPd, and ZrCo, which are isovalent species which possess ~or are thought to possess! an X 2?+ ground state. Several electronic band systems have been observed for these species in the near infrared, and the analysis of these systems is reported. Ground state vibrational intervals of ?G"1/2=334.5 ? 1.0, 264.4?0.2, and 357.7 cm-1 have been determined for ScNi, YPd, and ZrCo, respectively. The spectroscopic results obtained for ScNi and YPd are compared to theoretical calculations performed by other researchers, and a discussion of the chemical bonding in these species is presented