The nature of the lowest excited state of rhenium and copper complexes of dipyrido[3,2-a:2&#8242; ,3&#8242;-c]phenazine (Dppz) has been determined using Resonance Raman, Time-Resolved Resonance Raman Spectroscopy and Spectroelectrochemistry. Comparisonof spectroelectrochemical data and excited state data show that for the complexesstudied no reduced ligand bands are observed in the excited state spectra thus the lowestexcited states are all Ligand Centred in nature. The use of substituents at the 11 and/or12 position of the ligand has no effect on the excited state ordering.

Mark R. Waterland

Keith C. Gordon

Determination of the LowestExcited State of Metal Complexesof Dipyrido[3, 2-a:2&#8242;,3&#8242;-c]Phenazine

Step-scan Fourier transform absorption difference time-resolved spectroscopy (S2FTIR&#8710;A TRS) has been used to collect mid-IR time-resolved infrared spectra of the transientelectronic excited states of polypyridine transition metal complexes with 10 ns timeresolution. The time-resolved data can be used for kinetic analysis or to generate&#8220;snapshots&#8221; of the lowest lying excited state. Shifts of vibrational bands in the excitedstate relative to the ground state can be used to infer significant details of the electronicstructure of the excited state. The multiplex advantage of the FTIR technique allows awide variety of vibrational bands to be analyzed for this purpose. In the exampleillustrated, the shift of the ester &#957;(CO) band in {Ru(bpy)[4,4&#8242;-(COOEt)2bpy]2}2+compared to those in related complexes has been used to address the question of electrondelocalization in the excited state.

Gregory D. Smith

Pingyun  Chen

James L. Chao

Kristin M. Omberg

Darius A. Kavaliunas

Joseph A. Treadway

Thomas J. Meyer

Richard A. Palmer

Step-Scan Fourier TransformInfrared Absorption DifferenceTime-Resolved SpectroscopyStudies of Excited State DecayKinetics and Electronic Structureof Low-Spin d6 Transition MetalPolypyridine Complexes With 10Nanosecond Time Resolution

Recent developments of nonlinear spectroscopy in liquids are reviewed. Especially, off-resonantfifth and seventh order nonlinear techniques are discussed in light of theirapplication to the studies of microscopic dynamics. Vibrational echo experiments andovertone vibrational dephasing spectroscopy are examples of the higher order nonlinearspectroscopy.

Keisuke  Tominaga

Recent Development of NonlinearSpectroscopy in Liquids

We have used fast Time-resolved Infrared Spectroscopy (TRIR) to probe organometallicreactions in supercritical fluids on the nanosecond time-scale. This has allowed us toidentify, for the first time in solution at room temperature, organometallic noble gascomplexes which are formed following irradiation of metal carbonyls in supercriticalnoble gas solution. We have found that these complexes are surprisingly stable and havecomparable reactivity to organometallic alkane complexes. We have also studied the coordinationof CO2 to metal centres in supercritical CO2 (scCO2) and provide the firstevidence for the formation and reactivity of &#627;1-O bound metal CO2 complexes insolution at or above room temperature.

Michael W. George

Martyn  Poliakoff

Xue-Zhong  Sun

David C. Grills

Time-Resolved InfraredSpectroscopy in SupercriticalFluids

We present the simulations and analysis of the two-color ZEKE spectra of naphthalene,performed with the help of quantum chemical calculations of molecular parametersfollowed by the modelling of vibronic intensities. Ab initio and semi-empiricalcalculations were carried out to obtain molecular structures of neutral and ionicnaphthalene, and vibronic perturbations that couple the electronic states. It is shownthat the intensities, simulated with a model based on the perturbative expansion ofvibronic states, nicely reproduce the observed spectra and contribute to reassign some ofthe ground state frequencies of naphthalene cation.

Fabrizia  Negri

Marek Z. Zgierski

Theoretical Simulationof the Zeke Spectra ofNaphthalene From SingleVibronic Levels of S1

A time resolved resonance Raman (TR3) study of 1-nitronaphthalene (1NN) first tripletexcited state in various solvents is combined with ab initio calculations to determine thenature and the geometry of this state in environments of different polarity. A transientabsorption and TR3 study of the reactions of triplet 1NN with trans-stilbene (tS) insolution in both non-polar and polar solvents is reported. In polar solution, 31NN actsas an electron acceptor whereas in non-polar solution only energy transfer to tS isobserved. Moreover, at high concentrations of tS, the radical cation tS+ reacts withground-state tS to form a dimer radical cation (tS2)+. Differences between the Ramanspectra of the monomeric and the dimeric radical cations are reported in the 1500&#8211;1650 cm-1 region. The switch from energy to electron transfer when going from nonpolarto polar solutions is discussed in terms of the Marcus-Hush theory of electron transfer.

T.  Fournier

G. D. Scholes

I. R. Gould

S. M. Tavender

D.  Phillips

A. W. Parker

Triplet 1-Nitronaphthalene andCompetitive Energy and ElectronTransfer Reactions WithTrans-Stilbene

A six-wave set-up is described to determine molecular dynamics in the condensed phase.Applying two independent time delays between excitation and probe pulses additionalinformation on the dynamics should be obtainable. We show experimentally that suchinvestigations can be carried out with noisy light having intensity fluctuations in thefemtosecond region. As first result we found a fast relaxation time in neat nitrobenzeneof 100 fs, becoming even faster in mixtures with low viscosity liquids. Switching on aRaman resonance yields a longer relaxation time, which could be explained by anadditional contribution by that vibration.

A.  Lau

M.  Pfeiffer

V.  Kozich

A.  Kummrow

Molecular Dynamics Investigatedby Temporally Two-DimensionalCoherent Raman Spectroscopy

We have obtained A-band absorption resonance Raman spectra of 1-chloro-2-iodoethane in cyclohexane solution. We have done preliminary time-dependentwavepacket calculations to simulate the resonance Raman intensities and absorptionspectrum in order to learn more about the short-time photodissociation dynamics. Wecompare our preliminary results for 1-chloro-2-iodoethane with previous resonanceRaman results for iodoethane and find that there appears to be more motion along non-C&#8212;I stretch modes for 1-chloro-2-iodoethane than for iodoethane. This isconsistent with results of TOF photofragment spectroscopy experiments which indicatemuch more internal excitation of the photoproducts from 1-chloro-2-iodoethanephotodissociation than the photoproducts from iodoethane photodissociation.

Xuming  Zheng

David Lee Phillips

Short-Time PhotodissociationDynamics of 1-Chloro-2-IodoethaneFrom Resonance RamanSpectroscopy

Time-resolved resonance Raman and absorption spectra have revealed that thephotoinduced intramolecular hydrogen transfer reaction of ortho nitrobenzyl compoundsis initiated by the abstraction of methylene hydrogen by the ortho nitro group togenerate the ortho aci-nitro acid isomer. In polar solvents the ortho aci-nitro acid isdissociated into the aci-nitro anion and a proton, and the proton is captured by otherhydrogen accepting sites, such as 2-pyridyl, 4-pyridyl and 4-nitro groups to generate theortho N&#8212;H quinoid, para N&#8212;H quinoid and para aci-nitro acid isomers, respectively.For 2-nitroethylbenzene and 2- and 4-(2&#8242;-nitrobenzyl)pyridines the structure of theaci-nitro anion is very similar to that of their respective ortho aci-nitro acid, while for2,4-dinitroethylbenzene the structure of the aci-nitro anion quite resembles that of thepara aci-nitro acid.

Hiroaki  Takahashi

Yoshiki  Watanabe

Makoto  Sakai

Masanori  Tachikawa

Photoinduced IntramolecularHydrogen Transfer Reaction ofOrtho Nitrobenzyl Compounds

The lowest excited singlet state (S1) of 4,4&#8242;-bipyridine (44BPY) has been studied in waterand methanol by using pump-probe time-resolved resonance Raman spectroscopy in thepicosecond time domain. Spectroscopic evidence for a disymmetric S1 structure withlocalization of the electronic excitation in one of the two pyridyl rings is given. The fastformation of the N-hydro radical 44BPY<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mtext>H</mml:mtext><mml:mo>&#x2022;</mml:mo></mml:msup></mml:mrow></mml:math> from the S1 state is clearly observed inmethanol.

G.  Buntinx

L.  Bussotti

V.  De Waele

C.  Didierjean

O.  Poizat

Picosecond Raman Investigationof the Structure and Reactivityof 4,4&#8242;-Bipyridine in the S1 State

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Laser Chemistry | Hindawi

Laser Chemistry

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Laser Chemistry

Proceedings of the Eighth Conference on Time-Resolved Vibrational Spectroscopy

Proceedings of the Eighth Conference on Time-Resolved Vibrational Spectroscopy

Articles

Determination of the Lowest Excited State of Metal Complexes of Dipyrido[3, 2-a:2′,3′-c]Phenazine

Step-Scan Fourier Transform Infrared Absorption Difference Time-Resolved Spectroscopy Studies of Excited State Decay Kinetics and Electronic Structure of Low-Spin d⁶ Transition Metal Polypyridine Complexes With 10 Nanosecond Time Resolution

Recent Development of Nonlinear Spectroscopy in Liquids

Time-Resolved Infrared Spectroscopy in Supercritical Fluids

Theoretical Simulation of the Zeke Spectra of Naphthalene From Single Vibronic Levels of S₁

Triplet 1-Nitronaphthalene and Competitive Energy and Electron Transfer Reactions With Trans-Stilbene

Molecular Dynamics Investigated by Temporally Two-Dimensional Coherent Raman Spectroscopy

Short-Time Photodissociation Dynamics of 1-Chloro-2-Iodoethane From Resonance Raman Spectroscopy

Photoinduced Intramolecular Hydrogen Transfer Reaction of Ortho Nitrobenzyl Compounds

Picosecond Raman Investigation of the Structure and Reactivity of 4,4′-Bipyridine in the S₁ State