The Quest to Quit: an Exploration of the Cessation - Relapse Cycle of Cigarette Smoking

The smoker's perspective is seldom sought in cessation research. Consequently, cessation approaches may be less effective because they are not based on assumptions and interpretations shared by those who smoke. Understanding how chronic relapsing smokers interpret their predicament could enhance cessation approaches, improving the chances for complete, permanent cessation. To generate such an understanding, five participants were recruited who had attempted to quit smoking several times. Aiming for depth rather than breadth, multiple interviews were conducted with each participant, who also kept an event diary, recording current smoking, nicotine withdrawal, lapsing and relapsing. Narratology, a biographical method of symbolic interactionism drawing on thematic, structural, and dialogic analysis, was used to elicit the participants' points of view from interview and diary data. The findings show that participants make sense of their chronic relapsing through a master narrative of 'willpower versus weakness'. Meanwhile, the tobacco control domain is largely driven by 'cost', and subsidised treatments are driven by the 'addiction' master narrative. This gap between ways of making sense of smoking and relapse can cause self-stigma, reducing the likelihood that quitting will be attempted and that quit attempts will succeed. Changes are proposed to mitigate the negative effects on self-efficacy brought about through the present approach to tobacco control. Ways to improve the effectiveness of existing treatments are suggested. Finally, the value of the narrative method is highlighted, with suggestions for its use in research where elucidating the insider point of view may improve treatment outcomes

Identifying the Hydrogenated Planar Tetracoordinate Carbon: A Combined Experimental and Theoretical Study of CAl₄H and CAl₄H^–

The chemical curiosity “planar tetracoordinate carbon” (ptC) has greatly broadened one’s knowledge of molecular bonding motifs apart from the traditional, tetrahedral, van’t Hoff and LeBel’s concept. Synthesized ptC examples have been reported either in the solid state or in the gas phase, where the ptC core is usually metalized or organometallized. Surprisingly, there has been no experimental report on hydrogenated ptC to date. A possible answer to this situation could be the “promiscuity” of hydrogen when binding to other elements, which frustrates the formation of stable ptC that is in competition with other structures. In this Letter, we for the first time identified two hydrogenated ptC species, CAl₄H and CAl₄H^–, based on a photoelectron spectroscopic and quantum chemical study. The favorable site-selectivity of hydrogen was shown to be the bridge of the Al–Al bond rather than the terminus of Al, manifesting the thermodynamic preference of the 17e/18e counting rule over the 15e/16e rule

PtZnH₅^–, A σ‑Aromatic Cluster

We report a joint photoelectron spectroscopic and theoretical study of the PtZnH₅^– cluster anion. This cluster exhibited an unprecedented planar pentagonal coordination for Pt and an unusual stability and high intensity in the mass spectrum. Both are due to the σ-aromaticity found in the H₅-cycle supported by the 5d orbitals on the Pt atom. σ-Aromaticity in all-H systems has been predicted in the past but never found in experimentally observed species. Besides fundamental importance, mixed transition-metal hydrides can be found as intermediates in catalytic processes, and thus, the unexpected stability facilitated by σ-aromaticity can be appreciated also in practical applications

Photoelectron Spectroscopy and Computational Modeling of Thymidine Homodimer Anions

The intact thymidine homodimer anion (dT₂^–) was generated in the gas phase using an infrared desorption/photoemission source and recorded by a pulsed photoelectron spectrometer. The photoelectron spectrum (PES) revealed a broad signal with the maximum at electron binding energy ∼2.0 eV and the threshold value at 1.1 eV. The relative energies and vertical detachment energies of the possible anion structures were calculated at the B3LYP/6-31++G­(d,p) level. Here we report that the most stable anion radical homodimer geometries observed in the PES are the anionic nucleoside coordinated by the O8 atom of thymine to the deoxyribose of the second neutral nucleoside. Unlike previous experimental–computational studies on anionic complexes involving nucleobases with proton donors, the electron-induced proton-transferred structures are not responsible for the shape of the PES of dT₂^–

Excess Electron Attachment to the Nucleoside Pair 2′-Deoxyadenosine (dA)–2′-Deoxythymidine (dT)

The 2′-deoxyadenosine···2′-deoxythymidine (dAdT^•–) radical anion nucleoside pair has been investigated both experimentally and theoretically in the gas phase. The vertical detachment energy (VDE) and adiabatic electron affinity (AEA) were determined by anion photoelectron spectroscopy (PES). The measured photoelectron spectrum features a broad band having an onset at ∼1.1 eV and a maximum at the electron binding energy (EBE) ranging from 1.7 to 1.9 eV. Calculations performed at the M06-2X/6-31++G** level reveal that the observed PES signal is probably due to a dAdT^•– complex in which the thymine of the dT nucleoside forms hydrogen bonds that engage its O7 and O8 atoms as well as the 3′- and 5′-hydroxyl groups of 2′-deoxyadenosine (dA), while dT’s 3′-hydroxyl group interacts with the N1 of dA. In this heterodimer, the excess electron is entirely located on thymine. The biologically relevant Watson–Crick arrangement of the dAdT^•– dimer was found to be substantially less stable (by ∼19 kcal mol^–1 in Gibbs free energy scale) than the above-mentioned configuration; hence, it is not populated in the gas phase

Borane–Aluminum Surface Interactions: Enhanced Fracturing and Generation of Boron–Aluminum Core–Shell Nanoparticles

We present an experimental and theoretical study of borane–aluminum surface interactions that lead to rapid production of aluminum nanoparticles when Al balls are milled in the presence of diborane or pentaborane. Mass spectrometry was used to probe reactions of the boranes with aluminum fracture surfaces produced by milling collisions, which also generate local, transient high temperatures. Density functional theory was used to examine the interactions between a model aluminum surface and diborane and pentaborane, providing insight into the energetics of the first steps in the process that ultimately enables nanoparticle production. Further insight into the surface chemistry was obtained by analyzing the nanoparticles with X-ray photoelectron spectroscopy, scanning transmission electron microscopy with both electron-energy-loss and energy-dispersive X-ray spectroscopies, and dynamic light scattering. Particles were found to have fcc aluminum cores, capped by a ∼2-nm-thick shell, rich in both boron and hydrogen. The shell partially protects the aluminum from air oxidation, and further capping of the particles with organic ligands renders the particles air-stable and confers dispersibility in hydrocarbon solvents

How to Find Out Whether a 5‑Substituted Uracil Could Be a Potential DNA Radiosensitizer

Incorporated into genomic DNA, 5-substituted uracils could be employed in human cancer radiotherapy if they could be sensitized to dissociate upon reaction with hydrated electrons. Using the B3LYP/6-31++G­(d,p) method, we calculate electron affinities and energy profiles related to the dissociation of the respective anions for a series of uracil derivatives. We demonstrate that for a uracil analogue to be an efficient electron acceptor the uracil substituent has to possess significant electron-withdrawing power. On the other hand, in order to ensure effective dissociation of the anion, the chemical bond holding together the substituent and uracil residue should be relatively weak. Our theoretical predictions are in excellent agreement with the results of our negative ion photoelectron spectroscopy experiments. We propose two new potential sensitizers that seem to possess the required properties, although they have never been tested in radiobiological experiments

Dipole-Bound Anions of Intramolecular Complexes

Dipole-bound molecular anions are often envisioned as unperturbed neutral, polar molecules with single excess electrons. We report the observation of intramolecular structural distortions within silatrane molecules due to the formation of their dipole-bound anions. The combination of Rydberg electron transfer–anion photoelectron spectroscopy (RET-PES) and ab initio computational methodologies (CCSD and MP2) was used to study 1-hydro- (<b>HS</b>) and 1-fluoro- (<b>FS</b>) silatranes and their dipole bound anions, <b>HS</b>^<b>–</b> and <b>FS</b>^<b>–</b>. The vertical detachment energies (VDEs) of <b>HS</b>^<b>–</b> and <b>FS</b>^<b>–</b> were measured to be 48 and 93 meV, respectively. Ab initio calculations accurately reproduced these VDE values as well as their photoelectron spectral profiles. This work revealed significant shortening (by ∼0.1 Å) of dative Si ← N bond lengths when <b>HS</b> and <b>FS</b> formed dipole-bound anions, <b>HS</b>^<b>–</b> and <b>FS</b>^<b>–</b>. Detailed computational (Franck–Condon) analyses explained the absence of vibrational features in the photoelectron spectra of <b>HS</b>^<b>–</b> and <b>FS</b>^–

Electronic Structure and Anion Photoelectron Spectroscopy of Uranium–Gold Clusters UAu_<i>n</i>^–, <i>n</i> = 3–7

A collaborative effort between experiment and theory toward elucidating the electronic and molecular structures of uranium–gold clusters is presented. Anion photoelectron spectra of UAun–(n = 3–7) were taken at the third (355 nm) and fourth (266 nm) harmonics of a Nd:YAG laser, as well as excimer (ArF 193 nm) photon energies, where the experimental adiabatic electron affinities and vertical detachment energies values were measured. Complementary first-principles calculations were subsequently carried out to corroborate experimentally determined electron detachment energies and to determine the geometry and electronic structure for each cluster. Except for the ring-like neutral isomer of UAu6 where one unpaired electron is spread over the Au atoms, all other neutral and anionic UAun clusters (n = 3–7) were calculated to possess open-shell electrons with the unpaired electrons localized on the central U atom. The smaller clusters closely resemble the analogous UFn species, but significant deviations are seen starting with UAu5 where a competition between U–Au and Au–Au bonding begins to become apparent. The UAu6 system appears to mark a transition where Au–Au interactions begin to dominate, where both a ring-like and two heavily distorted octahedral structures around the central U atom are calculated to be nearly isoenergetic. With UAu7, only ring-like structures are calculated. Overall, the calculated electron detachment energies are in good agreement with the experimental values

On the Existence of Designer Magnetic Superatoms

The quantum states in small, compact metal clusters are bunched into electronic shells with electronic orbitals resembling those in atoms, enabling classification of stable clusters as superatoms. The filling of superatomic orbitals, however, does not generally follow Hund’s rule, and it has been proposed that magnetic superatoms can be stabilized by doping simple metal clusters with magnetic atoms. Here, we present evidence of the existence of a magnetic superatom and the determination of its spin moment. Our approach combines first principles studies with negative ion photoelectron experiments and enables a unique identification of the ground state and spin multiplicity. The studies indicate VNa₈ to be a magnetic superatom with a filled d-subshell and a magnetic moment of 5.0 μ_B. Its low electron affinity is consistent with filled subshell and enhanced stability. The synthesis of this species opens the pathway to investigate the spin-dependent electronics of the new magnetic motifs