Comparison of gas-phase free-radical populations in tobacco smoke and model systems by HPLC.

We used an improved method for trapping carbon-centered radicals (.R) from the gas-phase to compare radical suites trapped from various tobacco smoke and model smoke systems. Using a nitroxide trap, 3-amino-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (3AP), on solid support, we trapped radicals directly from the gas phase, washed them off the support, and analyzed them with HPLC. Separation of the trapped radicals showed that each tobacco type produced a unique radical suite of 4-10 distinct peaks. Gas mixtures used to model tobacco smoke consisted of nitric oxide, air, isoprene, and methanol. The model systems produced radical suites of four major and several minor peaks, two of which matched peaks in tobacco smoke chromatograms. Quantities of radicals trapped from tobacco smoke were: 54 +/- 2 nmol .R per Marlboro cigarette, 66 +/- 9 nmol .R per Djarum clove cigarette, and 185 +/- 9 nmol .R per Swisher Sweet cigar. In these experiments oxygen competes with the nitroxide trap for gas-phase radicals. A kinetic analysis of the O2 competition shows that actual radical concentrations in the smoke were approximately 100-fold higher than measured

Cross-Cultural Differences in Interpersonal and Intrapersonal Understandings of Forgiveness

Most theorizing about forgiveness conceptualize forgiveness as an intrapersonal process in which negative feelings are transformed into positive ones, with the goal of inner peace for the forgiver. Forgiveness viewed as an interpersonal process, in contrast, focuses on behaviors, such as reconciliation, that lead to the restoration of social harmony. Several studies have demonstrated that the understanding and practice of forgiveness differs across cultures. We examined the hypothesis that North Americans understand forgiveness as more of an intrapersonal phenomenon and less of an interpersonal phenomenon relative to Asians. A sample of 153 participants recruited through Facebook completed an online survey. Findings generally support the hypothesis: North Americans endorsed intrapersonal over interpersonal understandings of forgiveness, Southeast Asians endorsed interpersonal over intrapersonal understandings, and South Asians were closely split between the two definitions. The current findings suggest that collectivistic forgiveness is not a unitary construct, and that the application of theory and therapy models based on Western conceptions of forgiveness to Asian populations may be inaccurate and even harmful. Future research should examine forgiveness across collectivistic cultures. Additionally, cross-cultural research on forgiveness should use specific affective, cognitive, and behavioral terms when assessing a participant’s level of forgiveness; broad questions assessing a participant’s general forgiveness may be difficult to interpret and compare cross-culturally

Electron impact investigation of electronic excitations in furan, thiophene, and pyrrole

The electronically excited states of furan, thiophene, and pyrrole have been studied by electron impact at scattering angles from 0° to 80°, and impact energies of 30 and 50 eV. Low-lying features at 3.99 and 5.22 eV in furan, 3.75 and 4.62 eV in thiophene, and 4.21 eV in pyrrole are identified as singlet --> triplet transitions. The locations and, for furan and thiophene, the energy splittings of these excitations suggest that they are analogous to the lowest pi --> pi* singlet --> triplet transitions in benzene, and that these heterocycles have appreciable aromatic character. A weak feature observed in pyrrole at 5.22 eV is attributed to an optically forbidden singlet --> singlet transition. In all three molecules, transitions to several superexcited states are observed

Electronic spectroscopy of s-trans 1,3-butadiene by electron impact

The electron impact excitation of 1,3-butadiene has been studied experimentally at impact energies of 20, 35, and 55 eV and scattering angles from 10° to 85°. The energy and angular dependences of the cross section ratios are used to identify the nature of the excited states. Two transitions with maxima at 3.22 and 4.91 eV are identified as singlet-->triplet transitions. Comparison with theoretical calculations indicates that these are due to the 13Bu and 13Ag states, respectively. Their significance for the photochemistry of this molecule is discussed. The optically allowed X-tilde 1Ag --> 11Bu(N --> V1) transition is observed with a maximum at 5.92 eV. An additional transition appears between 6.9 and 7.8 eV with vibrational features at 7.09, 7.28, and 7.46 eV. The optical absorption in this region was originally attributed to a 1A1 state of the s -cis molecule and subsequently to a Rydberg state or to a 1Ag state of the s -trans molecule. On the basis of intensity arguments and the angular dependence of the cross section ratios, we suggest that it may instead be due to the X-tilde 1Ag --> 21Bu transition of the s -trans molecule. Rydberg transitions are observed at 8.00 and 8.18 eV. Two broad transitions are also seen beyond the first ionization potential with maxima at 9.50 and 11.00 eV. The results of this study are in good agreement with recent ab initio configuration interaction (CI) calculations, and give support to the analysis of the valence excited states in terms of a "molecules-in-molecules" approach. This is consistent with recent interpretations of the resonance energy and reactivity of this molecule and differs from the older classic model of extensive delocalization in the pi electron system

Electronic spectroscopy of propadiene (allene) by electron impact

The electron impact excitation of propadiene (allene) has been studied experimentally at impact energies of 20, 40, and 60 eV and scattering angles from 6° to 80°. Two transitions with maxima at 4.28 and 4.89 eV are identified as singlet --> triplet excitations. The magnitude of the splitting between these transitions is a measure of the interaction between the two perpendicular pi molecular orbitals. The significance of these triplet excited states in the interpretation of previous electronic energy transfer experiments and sensitized photochemical studies is briefly discussed. Two very weak transitions are observed between 5.0 and 6.5 eV. The angular dependence of the corresponding cross sections indicates that these are spin-allowed but symmetry-forbidden transitions. A weak singlet --> singlet transition is seen with a maximum at 6.74 eV. This feature has also been optically observed and attributed to an electric dipole-allowed χ 1A1-->1 1E transition. This assignment is discussed in the light of the present results. The first strong transition, the χ 1A1-->1 1B2 pi-->pi* transition, appears with a maximum at 7.24 eV. Higher energy-loss features between 7.95 and 10 eV probably involve excitations to Rydberg states. A previously unreported transition to a superexcited state is observed with a maximum at 11.25 eV

Variable angle electron-impact excitation of nitromethane

The electron-impact excitation of nitromethane has been studied at incident electron energies of 25, 55, and 90 eV, at scattering angles from 6° to 80°. The lowest-lying inelastic process which is observed is a previously unreported feature with a maximum intensity at 3.8 eV energy loss. This feature represents at least one singlettriplet transition. It is likely that this 3.8 eV triplet feature plays a central role in the gas phase photolysis of nitromethane. A weak inelastic process with a peak at 4.45 eV has also been observed, as has a strong transition at 6.23 eV. Both of these excitations are well known from optical spectra, and they are generally believed to represent spin-allowed n→π* and π→π* transitions, respectively. Their assignments are discussed in detail. In addition, seven other transitions, several of which have not been reported previously, have been detected in the 7–12 eV energy-loss range. Three of these transitions, at 8.3, 8.85, and 11.73 eV energy loss, are tentatively assigned to Rydberg excitations of increasingly tightly bound electrons into a 3s Rydberg orbital

Distinguished non-Archimedean representations

For a symmetric space (G,H), one is interested in understanding the vector space of H-invariant linear forms on a representation \pi of G. In particular an important question is whether or not the dimension of this space is bounded by one. We cover the known results for the pair (G=R_{E/F}GL(n),H=GL(n)), and then discuss the corresponding SL(n) case. In this paper, we show that (G=R_{E/F}SL(n),H=SL(n)) is a Gelfand pair when n is odd. When $n$ is even, the space of H-invariant forms on \pi can have dimension more than one even when \pi is supercuspidal. The latter work is joint with Dipendra Prasad

Excited electronic states of cyclohexene, 1,4-cyclohexadiene, norbornene, and norbornadiene as studied by electron-impact spectroscopy

The excited electronic states of cyclohexene, 1,4-cyclohexadiene, norbornene (bicyclo[2.2.1]-2-heptene), and norbornadiene (bicyclo-[2.2.1]-2,5-heptadiene) have been studied by electron impact at scattering angles from 5° to 80°, and impact energies of 30 and 50 eV. Low-lying features with intensity maxima at 4.24 eV in cyclohexene and 4.10 eV in norbornene are identified as singlet --> triplet transitions. Similar features in the spectra of 1,4-cyclohexadiene and norbornadiene extending from 3.4 to 5.4 eV and 2.9 to 4.5 eV, respectively, are believed to result from superposition of two low-lying singlet --> triplet transitions in each molecule. In norbornadiene these features have estimated intensity maxima at 3.4 and 3.9 eV, while in 1,4-cyclohexadiene they appear to be more highly overlapped, yielding a single intensity maximum at 4.29 eV. The singlet --> singlet excited state spectra of these molecules are discussed from the point of view of a model in which ethylene units interact via through-bond and through-space effects. In each of these four molecules, transitions to several superexcited states are observed