R2PI detection and spectroscopy of van der Waals clusters of styrene with simple molecules (original) (raw)
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R2PI detection and spectroscopy of van der Waals complexes of 4-fluorostyrene with rare gases
Chemical Physics Letters, 1995
One-color resonance-enhanced two-photon ionization spectra of jet-cooled 4-fluorostyrene van der Waals complexes with Ne, Ar, Kr, Xe are reported. The measured spectra display discrete structure and allow the identification of electronic spectral shifts as well as stretching and bending frequencies of the various complexes. These spectra are interpreted with the help of simple model calculations. 0009-2614/95/$09.50 6 1995 Elsevier Science B.V. All rights reserved SSDI 0009-2614(95)00264-2
Resonant two-photon ionization spectra of p-difluorobenzene mixed van der Waals complexes
Journal of Molecular Structure, 2009
Van der Waals heterodimers of p-difluorobenzene (DFB) with other molecules, prepared in a supersonic jet beam expansion, were studied by resonant two-photon ionization (R2PI) through their S 1 S 0 transition. The functional molecule in these systems is DFB. The partners-molecules are: p-difluorobenzene (homodimer), fluorobenzene, 1,3,5-trifluorobenzene, furan, N-methylpyrrole, ethanol and propargyl alcohol. In each case, the recorded spectra are relatively broad as the result of at least two structures present in the molecular beam. Using hexafluorobenzene or pyrrole as partners of DFB, the S 1 S 0 transition of the respective heterodimer was not detected. Intracluster ion-molecule reactions have been observed in the cases of p-difluorobenzene with ethanol and propargyl alcohol.
Electronic spectroscopy of fluorobenzene Van der Waals molecules by resonant two-photon ionization
Chemical Physics, 1983
Van der Waals (vdW) clusters of fluorohenzene (FB). synthesized in a seeded supersonic rare-_g;ls expxwion were studied bv laser-induced. resonant two-photon ionization (RZPI) combined with TOF-mass spectrometry. The m&c&z xere excited near the FB monomeis vibronic origin of the S,(zz*) + S, transition (X,, = _ 1644 .A). The heterogeneous clusters FB-.L\r_ (n-= 4) showed specific shifts of the O-O band relative to X,, induced by vdW interaction (FB-Ar:-23 cm-': FB- .-Xr,:-46 cm-': FB-Ar,: +4.6 cm-'). Additional satellite bands appeared due to intermolecular photofru_gmsntation. A second band found for FB-Ar at 20 cm-' was assigned to ;I vdW vibration (v,,, = 43 cm-'). Similar rsbults were obtained for FB-KS; (!I c 3). The spectra of the homogeneous clusters F& and FB, were more complex. The dimer spectrum hho\ved two broad spectral features. one blue-the other red-shifted relative to X,,. Each one is probably due to 3 different ijomsr. The blue-shifted contained progressions. which were tentatively assigned to a vdW vibration with 10 cm-' in the ground and 15 cm-' in the excited stale. The [timer spectrum showed a broad blue-shifted absorption maximum with prominent blrnds at-2.6.-20.-29 and-50 cm-'-From the obsewed spectra the feasibility of cluster-specific spscwoscopy is discuascd.
Resonant two-photon ionization of fluorene rare-gas van der Waals complexes
The Journal of Chemical Physics, 1983
Resonant two-photon ionization combined with time-of-flight mass spectrometry was applied for the interrogation of the So --S I electronic-vibrational excitations of van der Waals complexes of fluorene (FL) with rare-gas atoms and N2 in supersonic jets. Energy-resolved and mass-resolved spectra of FL· Ne. FL· Ar. (n = 1-3), FL· Kr, FL· Xe, and FL· N, were recorded over the energy range 0-800 cm-I above the electronic origin of S I' The red microscopic spectral shifts of the electronic origins of FL . R (R = Ar, Kr, and Xe) complexes are dominated by dispersive interactions, being proportional to the polarizability of R. The vibrational level structure of FL . R. (R = Ar, Kr, and Xe) complexes exhibits intramolecular vibrational excitations of FL, as well as intermolecular vibrations, which involve the relative motion of FL and R in the complex. The spectra of FL· Ne and FL· N, reveal a rich vibrational structure in the vicinity of the electronic origin, indicating a substantial change of the nuclear configuration upon electronic excitation. Upper and lower bounds on the dissociation energies of FL· R (R = Ne, Kr, and Xe) and FL· Ar, were inferred from the vibrational level structure in the mass-resolved spectra, where the disappearance of the signal of the parent van der Waals ion and the appearance of the ion signal of the fragments mark the onset of the vibrational predissociation process.
2021
The study of van der Waals complexes provides a means for understanding the nature and strength of non-covalent interactions. Non-covalent interactions including C-H/, C-H/O, C-H/N, C-H/F, halogen and chalcogen bonding are found in important intermediates that regulate chemical and biological processes in many forefront areas of science including molecular self-assembly, drug substrate interactions, supramolecular chemistry, crystal engineering and biochemistry. To better understand these interactions, laser spectroscopic techniques that include mass selected two color resonant two photon ionization (2CR2PI) and velocity mapped ion imaging spectroscopy in combination with complementary ab initio calculations were used to probe the electronic structure, geometries, and binding strengths in aromatic van der Waals clusters. Prototypical systems of anisole ... (CH4)n, aniline ... (CH4)n (n=1,2) and toluene ...
Journal of Chemical Sciences, 1993
Research on the formation and properties of clusters of aromatic molecules bonded to numerous solvents is rapidly expanding. Recently much attention has been paid to these adduct species with the objective of clarifying nucleation phenomena. Photophysical and photochemical studies of these clusters give information on solvent effects, intracluster reactions and charge-transfer processes. Model calculations of potential surfaces of vdW adducts have provided knowledge of the intracluster binding energy and vdW vibrational modes in a few systems. Here, data are reported on resonant two-photon ionization R2PI mass spectra and on spectroscopic shifts of styrenes clustered with various atoms and molecules.
Resonant two-photon ionization combined with time-of-flight mass spectrometry was applied for the interrogation of the So --S I electronic-vibrational excitations of van der Waals complexes of fluorene (FL) with rare-gas atoms and N2 in supersonic jets. Energy-resolved and mass-resolved spectra of FL· Ne. FL· Ar. (n = 1-3), FL· Kr, FL· Xe, and FL· N, were recorded over the energy range 0-800 cm-I above the electronic origin of S I' The red microscopic spectral shifts of the electronic origins of FL . R (R = Ar, Kr, and Xe) complexes are dominated by dispersive interactions, being proportional to the polarizability of R. The vibrational level structure of FL . R. (R = Ar, Kr, and Xe) complexes exhibits intramolecular vibrational excitations of FL, as well as intermolecular vibrations, which involve the relative motion of FL and R in the complex. The spectra of FL· Ne and FL· N, reveal a rich vibrational structure in the vicinity of the electronic origin, indicating a substantial change of the nuclear configuration upon electronic excitation. Upper and lower bounds on the dissociation energies of FL· R (R = Ne, Kr, and Xe) and FL· Ar, were inferred from the vibrational level structure in the mass-resolved spectra, where the disappearance of the signal of the parent van der Waals ion and the appearance of the ion signal of the fragments mark the onset of the vibrational predissociation process.
Chemical Physics Letters, 1996
Laser-induced fluorescence spectra are presented for the first allowed electronic transitions in the near-UV of the aniline-argon and aniline-neon 1:1 Van der Waals complexes, formed in a molecular beam. The experimental linewidth was of the order of 10 -3 cm-t due to residual Doppler broadening and lifetime contributions. Single rotational eigenstates were resolved and complete sets of spectral assignments obtained using a rigid-rotor Hamiltonian model. From the rotational constants we extract both structural and dynamical information on the different clusters. This information is better understood in the light of a comparison with the results of quantum calculations.
The intermolecular vibrations of Ar–styrene and Ar–4-fluorostyrene complexes
The Journal of Chemical Physics, 1993
One-color (1-1-1) resonance enhanced multiphoton ionization (R EM PI) spectra are reported for styrene-Ar" clusters with n = 2, 3, and for 4-fluorostyrene-Ar" clusters with n-2-5. These spectra are compared with previously recorded spectra of the mono-Ar complexes and discussed in relation to the structures of the clusters. For the mono-Ar complexes we have performed practically exact quantum calculations of the van der Waals vibrational frequencies and prop erties, starting from two different empirical atom-atom potentials. The intermolecular potentials are strongly anharmonic and, due to the low symmetry of these dimers, we find considerable mode mixing. As a consequence of the kinematic coupling between the Ar motion and the internal rotation, the bending frequencies depend considerably on the different rotational con stants of the molecules. The order of the fundamental frequencies is the same for both dimers. For Ar-4-fluorostyrene the calculated vibrational frequencies agree well with the observed spectrum; the van der Waals side bands can thus be assigned in detail. For Ar-styrene the observed frequencies are less well reproduced, so we must conclude that the atom-atom poten tial used is substantially better for Ar-fluorostyrene than for Ar-styrene.