Semiempirical HSO-HO Cluster Standard Gibbs Reaction Energies from Nucleation Experiments: Improved Temperature Dependence.

The thermodynamics of sulfuric acid-water clusters is important for modeling new particle formation in the atmosphere. Particle number densities obtained at 296 K from a photolytic flow reactor are greatly overpredicted by the Sulfuric Acid Water Nucleation (SAWNUC) model. Empirical, temperature-dependent adjustments to the SAWNUC model allow for better agreement with the data obtained at 296 K, while maintaining reasonable agreement with the data of Hanson and Lovejoy at 242 K.

The Relationship Between Perceived Parenting Style and Social Anxiety: A Meta-analysis of Mainland Chinese Students.

Previous research on the relationship between parenting style and social anxiety in Chinese youth has been inconsistent, which has made it difficult to consider whether improving parenting may serve as a preventative intervention for social anxiety. The current study aimed to clarify these inconsistencies by examining the strength of the association between positive/negative parenting style and social anxiety among Chinese students and the role of certain moderators in those associations. A meta-analysis was conducted on 53 studies with a total sample of 26,024 Chinese mainland students.

Social change at the local level: A psychobiography of Khali Sweeney from Detroit's downtown boxing gym.

Objective: This psychobiography analyzes the life of Khali Sweeney from Detroit's Downtown Boxing Gym to understand his motivation for and methods as a social change agent. In doing so, the project also considers how to prepare the next generation of youth development leaders as social change agents.

Method: We conducted a nine-step psychobiography based on recommendations from established psychobiographical methods.

Stepping in and up to meet community needs: How community-based college access and success programs responded to COVID-19.

The current study uplifts the efforts of community-based college access and success programs (CAS) to support the college preparation, matriculation, and persistence of underserved students during COVID-19. Fifty-eight CAS across the United States completed an online survey that gathered information about organizational demographics, COVID-19 challenges, responses to challenges, and communication with constituents and funding needs during COVID-19. Results suggested CAS faced multiple challenges due to COVID-19 that affected the organization, staff, and constituents.

First Evidence of Vibrationally Driven Bimolecular Reactions in Solution: Reactions of Br Atoms with Dimethylsulfoxide and Methanol.

We present evidence for vibrational enhancement of the rate of bimolecular reactions of Br atoms with dimethylsulfoxide (DMSO) and methanol (CHOH) in the condensed phase. The abstraction of a hydrogen atom from either of these solvents by a Br atom is highly endoergic: 3269 cm for DMSO and 1416 or 4414 cm for CHOH, depending on the hydrogen atom abstracted. Thus, there is no thermal abstraction reaction at room temperature.

Solvent Dependent Dynamics of Salicylidene Aniline in Binary Mixtures of Supercritical CO with 1-Propanol or Cyclohexane.

The role of different solvent environments in determining the behavior of molecules in solution is a fundamental aspect of chemical reactivity. We present an approach for exploring the influence of solvent properties on condensed-phase dynamics using ultrafast transient absorption spectroscopy in supercritical CO. Using supercritical CO permits adjustment of the density, by varying the temperature and pressure, whereas varying the concentration or identity of a second solvent, the cosolvent, in a binary mixture allows for adjustments of the degree of interaction between the solute and the solvent.

Dynamics and yields for CHBrCl photodissociation from 215-265 nm.

We investigate the Ã-band photodissociation of CHBrCl at 215, 225, 235, 245, 255, and 265 nm. Following C-Br bond cleavage, resonance enhanced multiphoton ionization and time of flight mass spectrometry provide selective detection of the two product channels, from which we quantify the relative quantum yield of Br/Br* production. Velocity-map imaging of the photofragments allows us to determine the energy partitioning as a function of the photolysis energy for different exit channels.

Comparative Study of Cl-Atom Reactions in Solution Using Time-Resolved Vibrational Spectroscopy.

A Cl atom can react with 2,3-dimethylbutane (DMB), 2,3-dimethyl-2-butene (DMBE), and 2,5-dimethyl-2,4-hexadiene (DMHD) in solution via a hydrogen-abstraction reaction. The large exoergicity of the reaction between a Cl atom and alkenes (DMBE and DMHD) makes vibrational excitation of the HCl product possible, and we observe the formation of vibrationally excited HCl (v = 1) for both reactions. In CCl4, the branching fractions of HCl (v = 1), Γ (v = 1), for the Cl-atom reactions with DMBE and DMHD are 0.

Vibrational predissociation and vibrationally induced isomerization of 3-aminophenol-ammonia.

We investigate the vibrational predissociation dynamics of the hydrogen-bonded 3-aminophenol-ammonia cluster (3-AP-NH3) in the OH and NH stretching regions. Vibrational excitation provides enough energy to dissociate the cluster into its constituent 3-AP and NH3 monomers, and we detect the 3-AP fragments via (1 + 1) resonance-enhanced multiphoton ionization (REMPI). The distribution of vibrational states of the 3-AP fragment suggests the presence of two distinct dissociation pathways.

Nonadiabatic photofragmentation dynamics of BrCN-.

The photofragmentation dynamics of BrCN(-) in the 270-355 nm and the 430-600 nm wavelength regions is explored both experimentally and theoretically. In the case of excitation between 430 nm and 600 nm, it is found that the molecular ion accesses two dissociation channels with a measured 60:40 branching ratio that is nearly constant over this range of photon energies. The dominant product channel corresponds to Br(-) + CN, while the second channel correlates to spin-orbit excited Br(*) with CN(-).

Electronic states of the quasilinear molecule propargylene (HCCCH) from negative ion photoelectron spectroscopy.

We use gas-phase negative ion photoelectron spectroscopy to study the quasilinear carbene propargylene, HCCCH, and its isotopologue DCCCD. Photodetachment from HCCCH– affords the X̃(3B) ground state of HCCCH and its ã(1A), b̃ (1B), d̃(1A2), and B̃(3A2) excited states. Extended, negatively anharmonic vibrational progressions in the X̃(3B) ground state and the open-shell singlet b̃ (1B) state arise from the change in geometry between the anion and the neutral states and complicate the assignment of the origin peak.

Photofragmentation dynamics of ICN(-)(CO2)n clusters following visible excitation.

Photodissociation of ICN(-)(CO2)n, n = 0-18, with 500-nm excitation is investigated using a dual time-of-flight mass spectrometer. Photoabsorption to the (2)Π(1/2) state is detected using ionic-photoproduct action spectroscopy; the maximum absorption occurs around 490 nm. Ionic-photoproduct distributions were determined for ICN(-)(CO2)n at 500 nm.

Dynamics of small, ultraviolet-excited ICN- cluster anions.

The ultraviolet (UV) photodissociation of mass-selected ICN(-)Ar(n) and ICN(-)(CO2)n clusters (n = 0-5) is studied using a secondary reflectron mass spectrometer. Relative photodissociation cross sections of bare ICN(-) show the dominance of the I(-) photoproduct from 270 to 355 nm, the entire wavelength range studied. UV excitation populates both the (2)Σ(+) state that produces I* + CN(-) and the (2)Π states that produce I(-) + CN*.

Ground and low-lying excited states of propadienylidene (H2C=C=C:) obtained by negative ion photoelectron spectroscopy.

A joint experimental-theoretical study has been carried out on electronic states of propadienylidene (H(2)CCC), using results from negative-ion photoelectron spectroscopy. In addition to the previously characterized X(1)A(1) electronic state, spectroscopic features are observed that belong to five additional states: the low-lying ã(3)B(1) and b(3)A(2) states, as well as two excited singlets, Ã(1)A(2) and B(1)B(1), and a higher-lying triplet, c(3)A(1). Term energies (T(0), in cm(-1)) for the excited states obtained from the data are: 10,354±11 (ã(3)B(1)); 11,950±30 (b(3)A(2)); 20,943±11 (c(3)A(1)); and 13,677±11 (Ã(1)A(2)).

Determining the dissociation threshold of ammonia trimers from action spectroscopy of small clusters.

Infrared-action spectroscopy of small ammonia clusters obtained by detecting ammonia fragments from vibrational predissociation provides an estimate of the dissociation energy of the trimer. The product detection uses resonance enhanced multiphoton ionization (REMPI) of individual rovibrational states of ammonia identified by simulations using a consistent set of ground-electronic-state spectroscopic constants in the PGOPHER program. Comparison of the infrared-action spectra to a less congested spectrum measured in He droplets [M.

New view of the ICN A continuum using photoelectron spectroscopy of ICN-.

Negative-ion photoelectron spectroscopy of ICN(-) (X̃ (2)Σ(+)) reveals transitions to the ground electronic state (X̃ (1)Σ(+)) of ICN as well as the first five excited states ((3)Π(2), (3)Π(1), Π(0(-) ) (3), Π(0(+) ) (3), and (1)Π(1)) that make up the ICN A continuum. By starting from the equilibrium geometry of the anion, photoelectron spectroscopy characterizes the electronic structure of ICN at an elongated I-C bond length of 2.65 Å.

Dynamic mapping of CN rotation following photoexcitation of ICN-.

In a spin: the dynamics of photoexcited ICN(-) (Ar)(0-5) are presented. Photodetachment produces quasi-thermal electron emission that leaves ICN with up to 2.85 eV of internal energy.

Dissociation energy and vibrational predissociation dynamics of the ammonia dimer.

Experiments using infrared excitation of either the intramolecular symmetric N-H stretch (ν(NH,S)) or the intramolecular antisymmetric N-H stretch (ν(NH,A)) of the ammonia dimer ((NH(3))(2)) in combination with velocity-map ion imaging provide new information on the dissociation energy of the dimer and on the energy disposal in its dissociation. Ion imaging using resonance enhanced multiphoton ionization to probe individual rovibrational states of one of the ammonia monomer fragments provides recoil speed distributions. Analyzing these distributions for different product states gives a dissociation energy of D(0) = 660 ± 20 cm(-1) for the dimer.

Dynamics at conical intersections: the influence of O-H stretching vibrations on the photodissociation of phenol.

Comparing the recoil energy distributions of the fragments from one-photon dissociation of phenol-d(5) with those from vibrationally mediated photodissociation shows that initial vibrational excitation strongly influences the disposal of energy into relative translation. The measurements use velocity map ion imaging to detect the H-atom fragments and determine the distribution of recoil energies. Dissociation of phenol-d(5) molecules with an initially excited O-H stretching vibration produces significantly more fragments with low recoil energies than does one-photon dissociation at the same total energy.

Vibrational action spectroscopy of the C-H and C-D stretches in partially deuterated formic acid dimer.

Vibrational action spectroscopy of jet-cooled formic acid dimer measures the frequency of the C-H(D) stretching vibration and its coupling to nearby states. The action spectrum of (DCOOH)2 reveals a specific Fermi resonance between the C-D stretch and two antisymmetric combination states formed from the C-O stretch and DCO bend. A three-state deperturbation analysis shows that there is a relatively strong coupling between the fundamental vibration and each of the combination vibrations (mid R:13 cm(-1)mid R:) as well as between the combination states themselves (mid R:7 cm(-1)mid R:).