Rotational Coherence Spectroscopy and Structure of Naphthalene Trimer

Benharash, Peyman; Gleason, Michael; Felker, Peter

doi:10.1021/jp984636c

Cited by 45 publications

(47 citation statements)

References 17 publications

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“…First, they reinforce the prior conclusion, made on the basis of vibronic, 3,8,10 vibrational, 3 and rotational 11 spec-troscopic results, as well as computational studies, 12,13 that naphthalene trimer is a C 3h species in which all of the naphthalene monomers are aligned with their long axes parallel. Second, they allow for an assignment of almost all of the intermolecular vibrational modes in the perprotonated and perdeuterated species ͑denoted h 3 and d 3 , respectively͒ and in the (h 8 ) 2 d 8 and h 8 (d 8 ) 2 mixed isotopomers ͑henceforth denoted h 2 d 1 and h 1 d 2 , respectively͒.…”

Section: Introductionsupporting

confidence: 81%

Intermolecular vibrations of naphthalene trimer by ionization-detected stimulated Raman spectroscopy

Kim

Schaeffer

Lee

et al. 1999

The Journal of Chemical Physics

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We present nonlinear Raman spectra of intermolecular vibrational transitions in four naphthalene trimer isotopomers. The spectra, measured at 0.03 cm Ϫ1 by mass-selective ionization-loss stimulated Raman spectroscopy, reveal distinctly shaped pendular band contours, which, upon comparison to simulated pendular contours, lead to ready assignments for almost all of the observed bands. The results show clearly that the trimer has C 3h ͑or very nearly C 3h ͒ symmetry with the naphthalenes arranged such that their long axes are parallel to one another. Comparison of the experimental results to the results of calculations of naphthalene-trimer intermolecular spectra performed by assuming harmonic intermolecular modes and by taking the intermolecular potential energy surface to be a pair-wise additive one reveals significant qualitative agreement. This agreement strongly suggests a relatively rigid cluster with no large amplitude intermolecular motions within 100 cm Ϫ1 of the zero-point level. Finally, the results highlight the dominance of librational motions in giving rise to scattering intensity in the intermolecular portion of the cluster's Raman spectrum.

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Section: Introductionsupporting

confidence: 81%

Intermolecular vibrations of naphthalene trimer by ionization-detected stimulated Raman spectroscopy

Kim

Schaeffer

Lee

et al. 1999

The Journal of Chemical Physics

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“…Small clusters of PAH molecules have been studied by several authors in the past, both experimentally (Benharash et al 1999;Song et al 2003;Piuzzi et al 2002;Miller et al 1984) and theoretically (van de Waal 1983;Gonzales & Lim 1999;Marzec 2000;Piuzzi et al 2002;Grimme 2004). Most of these studies have focused on rather small species, usually containing no more than a few tens of carbon atoms, far below the limit of 400 carbon atoms per VSG as suggested by Rapacioli et al (2005b).…”

Section: Introductionmentioning

confidence: 99%

Formation and destruction of polycyclic aromatic hydrocarbon clusters in the interstellar medium

Rapacioli¹,

Calvo

Joblin³

et al. 2006

A&A

139

145

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Aims. The competition between the formation and destruction of coronene clusters under interstellar conditions is investigated theoretically. Methods. The unimolecular nucleation of neutral clusters is simulated with an atomic model combining an explicit classical force field and a quantum tight-binding approach. Evaporation rates are calculated in the framework of the phase space theory and are inserted in an infrared emission model and compared with the growth rate constants. Results. It is found that, in interstellar conditions, most collisions lead to cluster growth. The time evolution of small clusters (containing up to 312 carbon atoms) was specifically investigated under the physical conditions of the northern photodissociation region of NGC 7023. These clusters are found to be thermally photoevaporated much faster than they are reformed, thus providing an interpretation for the lowest limit of the interstellar cluster size distribution inferred from observations. The effects of ionizing the clusters and density heterogeneities are also considered. Based on our results, the possibility that PAH clusters could be formed in PDRs is critically discussed.

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“…Calculations provided a test for quantum mechanical theories of molecular electronic structure (16,17). In recent years, detailed information about naphthalene clusters has been obtained through high-resolution rotational spectroscopy analysis (22,23). For example, structural information on naphthalene trimer has been extracted from rotational coherence spectroscopy (23).…”

mentioning

confidence: 99%

“…In recent years, detailed information about naphthalene clusters has been obtained through high-resolution rotational spectroscopy analysis (22,23). For example, structural information on naphthalene trimer has been extracted from rotational coherence spectroscopy (23). Excimer formation dynamics has been studied by Lim's group through fluorescence spectroscopy (24)(25)(26)(27)(28).…”

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confidence: 99%

Excitonic couplings and electronic coherence in bridged naphthalene dimers

Tretiak

Zhang

Chernyak

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

104

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The electronic excitations of naphthalene and a family of bridged naphthalene dimers are calculated and analyzed by using the Collective Electronic Oscillator method combined with the oblique Lanczos algorithm. All experimentally observed trends in absorption profiles and radiative lifetimes are reproduced. Each electronic excitation is linked to the corresponding real-space transition density matrix, which represents the motions of electrons and holes created in the molecule by photon absorption. Two-dimensional plots of these matrices help visualize the degree of exciton localization and explain the dependence of the electronic interaction between chromophores on their separation. R elating electronic excitations of molecular aggregates to those of the individual chromophores is a long-standing fundamental problem with numerous applications to organic superlattices and biological complexes (1, 2).Considerable effort has been devoted to clusters of the simplest aromatic molecules such as napthalene and benzene (3-7). Supersonic beam techniques have made it possible to study the excited-state dynamics and obtain detailed information about geometries and intermolecular interactions in these clusters (8-10). Naphthalene is one of the most thoroughly studied chromophores in crystals and in the gas phase both theoretically and experimentally (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). Calculations provided a test for quantum mechanical theories of molecular electronic structure (16,17). In recent years, detailed information about naphthalene clusters has been obtained through high-resolution rotational spectroscopy analysis (22, 23). For example, structural information on naphthalene trimer has been extracted from rotational coherence spectroscopy (23). Excimer formation dynamics has been studied by Lim's group through fluorescence spectroscopy (24-28). Excitonic interactions depend strongly on the distance and relative orientation of the transition moments of monomer units. The geometry can be obtained from high-resolution vibronic spectra and nonlinear Raman spectroscopy (10,22,29). Extensive study of benzene has been carried out as well. Recent interest focused on the structure and properties of benzene clusters (30-36). Isotopically mixed benzene clusters have been used in the investigation of intermolecular interactions. Discrete exciton spectra were observed for benzene dimers (9, 37).In this paper, we analyze the absorption spectra of naphthalene and a family of naphthalene-bridge-naphthalene systems DN-2, DN-4, and DN-6 (see Fig. 1) (38-41). These molecules may be regarded as naphthalene dimers where pairs of naphthalene chromophores are held at fixed distances and orientations by a rigid polynorbornyl-type bridge of variable length (two, four, or six bonds, respectively). The UV-spectra and radiative decay rates of these dimers have been measured (39-41) and interpreted by using a simple exciton model (42). Within this model, each excited state of the monomer generates two states in the dimer. The interac...

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Rotational Coherence Spectroscopy and Structure of Naphthalene Trimer

Cited by 45 publications

References 17 publications

Intermolecular vibrations of naphthalene trimer by ionization-detected stimulated Raman spectroscopy

Intermolecular vibrations of naphthalene trimer by ionization-detected stimulated Raman spectroscopy

Formation and destruction of polycyclic aromatic hydrocarbon clusters in the interstellar medium

Excitonic couplings and electronic coherence in bridged naphthalene dimers

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