A study on the structure and vibrations of diphenylamine by resonance-enhanced multiphoton ionization spectroscopy and ab initio calculations

Laser‐desorption jet‐cooling has been applied in combination with mass‐selective gas‐phase spectroscopic techniques to study the structure and low‐frequency vibrations of diphenylamine (DPA). Two‐color (1+1′) resonance‐enhanced multiphoton ionization has been used to measure the vibrationally resolved excitation spectrum of the S1←S0 transition in the 305–309 nm region. Ion‐dip measurements have been performed to determine the vibrational structure in the electronic ground state. The electronic spectra of DPA are dominated by long progressions in low‐frequency vibrations involving the motion of the phenyl rings as a whole. For the interpretation of the experimental data ab initio calculations have been performed at the Hartree–Fock level for the S0‐state and using single‐excitation configuration interaction for the S1‐state. The DPA molecule is found to change from a pyramidal geometry around the N‐atom with unequal torsional angles of the phenyl groups in the S0‐state to a planar geometry with equal torsional angles in the S1‐state. The two most prominent vibrational motions are the in‐phase wagging and the in‐phase torsion of the phenyl rings. In addition, the resonance‐enhanced multiphoton ionization spectra of the S1←S0 transition in the DPA‐Ar, DPA‐Kr, and DPA‐Xe van der Waals complexes have been measured. From these spectra it is inferred that there is a coupling between the van der Waals modes and the low‐frequency intra‐molecular modes of DPA

Infrared spectroscopy of jet-cooled neutral and ionized aniline-Ar

We report the infrared (IR) absorption spectrum of the jet-cooled neutral aniline–Ar Van der Waals complex together with that of the aniline–Ar cation in the 350–1700 cm−1 range. The spectra are measured using mass-selective ion detection in two different IR–ultraviolet double-resonance excitation schemes, using a free-electron laser as a source of widely tunable, intense IR radiation. A comparison with calculated IR spectra of the bare neutral aniline and of the cation of aniline allows for an unambiguous assignment of all the observed modes. The dissociation limit of the neutral aniline–Ar complex is bracketed between 273 and 329 cm−1, significantly lower than previously estimated. <br

The infrared spectrum of the benzene–Ar cation

The infrared (IR) absorption spectra of the jet-cooled C6H6 and C6D6 cations, complexed with Ar, are measured throughout the 450–1500 cm−1 region via IR-laser-induced vibrational dissociation spectroscopy. The IR spectrum of the C6H6–Ar cation is dominated by a Fermi resonance between the IR active v11 mode and two components of the combination mode of the lowest frequency modes v6 and v16 . A stringent upper limit of 316 cm−1 is found for the value of the dissociation limit D0 of the neutral C6D6–Ar complex

Cavity ring down spectroscopy on solid C₆₀

The light absorption of a solid sample in the 8.5 μm region is measured via cavity ring down (CRD) absorption spectroscopy, using a free electron laser (FEL) as a source of widely tunable infrared (IR) radiation. A 3 mm thick zinc-selenide (ZnSe) window is used as a substrate for a 20–30 nm thick C60 film. On top of the structureless absorption due to ZnSe (60 is measured with monolayer sensitivity

Infrared Resonance Enhanced Multiphoton Ionization of Fullerenes

Gas-phase fullerenes are resonantly heated by a train of high power subpicosecond pulses from a free electron laser (FEL) to internal energies at which they efficiently undergo delayed ionization. When the laser is tuned from 6–20μm while the amount of laser produced parent ions is recorded, resonant absorption of 200–600 IR photons, resulting in almost fragmentation-free ion spectra, is observed. Infrared resonance enhanced multiphoton ionization with a FEL is shown to enable extremely sensitive IR spectroscopy with mass selective detection of gas-phase fullerenes

Atomic clusters of magnetic oxides: Structure and phonons

This work represents a combined experimental and theoretical study of structural and magnetic properties of clusters made of cobalt, chromium, and manganese oxides. The clusters were prepared in a molecular cluster source by oxidation of laser-vaporized metal and studied in a time-of-flight spectrometer. Infrared laser-induced cluster dissociation experiments revealed the spectrum of cluster vibrational states. We also performed ab initio local spin density approximation calculations of the equilibrium geometry, electronic structure, and magnetic properties of these clusters

Unraveling the internal dynamics of the benzene dimer: a combined theoretical and microwave spectroscopy study

Contains fulltext : 111457.pdf (publisher's version ) (Open Access

Nazi Punks Folk Off: Leisure, Nationalism, Cultural Identity and the Consumption of Metal and Folk Music

Far-right activists have attempted to infiltrate and use popular music scenes to propagate their racialised ideologies. This paper explores attempts by the far right to co-opt two particular music scenes: black metal and English folk. Discourse tracing is used to explore online debates about boundaries, belonging and exclusion in the two scenes, and to compare such online debates with ethnographic work and previous research. It is argued that both scenes have differently resisted the far right through the policing of boundaries and communicative choices, but both scenes are compromised by their relationship to myths of whiteness and the instrumentality of the pop music industry

'Mine's a Pint of Bitter': Performativity, gender, class and representations of authenticity in real-ale tourism

Leisure choices are expressive of individual agency around the maintenance of taste, boundaries, identity and community. This research paper is part of a wider project designed to assess the social and cultural value of real ale to tourism in the north of England. This paper explores the performativity of real-ale tourism and debates about belonging in northern English real-ale communities. The research combines an ethnographic case study of a real-ale festival with semi-structured interviews with organisers and volunteers, northern English real-ale brewers and real-ale tourists visiting the festival. It is argued that real-ale tourism, despite its origins in the logic of capitalism, becomes a space where people can perform Habermasian, communicative leisure, and despite the contradictions of preferring some capitalist industries over others on the basis of their perceived smaller size and older age, real-ale fans demonstrate agency in their performativity

Carbon clusters near the crossover to fullerene stability

The thermodynamic stability of structural isomers of $\mathrm{C}_{24}$, $\mathrm{C}_{26}$, $\mathrm{C}_{28}$ and $\mathrm{C}_{32}$, including fullerenes, is studied using density functional and quantum Monte Carlo methods. The energetic ordering of the different isomers depends sensitively on the treatment of electron correlation. Fixed-node diffusion quantum Monte Carlo calculations predict that a $\mathrm{C}_{24}$ isomer is the smallest stable graphitic fragment and that the smallest stable fullerenes are the $\mathrm{C}_{26}$ and $\mathrm{C}_{28}$ clusters with $\mathrm{C}_{2v}$ and $\mathrm{T}_{d}$ symmetry, respectively. These results support proposals that a $\mathrm{C}_{28}$ solid could be synthesized by cluster deposition.Comment: 4 pages, includes 4 figures. For additional graphics, online paper and related information see http://www.tcm.phy.cam.ac.uk/~prck