Ultra: A Unique Instrument for Time-Resolved Spectroscopy

Greetham, Gregory M.; Burgos, Pierre; Cao, Qian; Clark, Ian P.; Codd, Peter S.; Farrow, R. C.; George, Michael W.; Kogimtzis, M.; Matousek, Pavel; Parker, Anthony W.; Pollard, Mark R.; Robinson, David; Xin, Z.J.; Towrie, Michael

doi:10.1366/000370210793561673

Cited by 175 publications

(191 citation statements)

References 35 publications

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“…All ultrafast experiments were performed at the ULTRA facility 48 at the Rutherford Appleton Laboratories, UK. Two synchronized 10 kHz titanium sapphire oscillator/regenerative amplifiers (Thales) pump a range of optical parametric amplifiers (TOPAS).…”

Section: Methodsmentioning

confidence: 99%

Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation

et al. 2017

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Ultrafast electron transfer in condensed-phase molecular systems is often strongly coupled to intramolecular vibrations that can promote, suppress and direct electronic processes. Recent experiments exploring this phenomenon proved that light-induced electron transfer can be strongly modulated by vibrational excitation, suggesting a new avenue for active control over molecular function. Here, we achieve the first example of such explicit vibrational control through judicious design of a Pt(II)-acetylide charge-transfer Donor-Bridge-Acceptor-Bridge-Donor "fork" system: asymmetric 13 C isotopic labelling of one of the two -C≡C-bridges makes the two parallel and otherwise identical Donor→Acceptor electron-transfer pathways structurally distinct, enabling independent vibrational perturbation of either. Applying an ultrafast UV pump (excitation)-IR pump (perturbation)-IR probe (monitoring) pulse sequence, we show that the pathway that is vibrationally perturbed during UV-induced electron-transfer is dramatically slowed down compared to its unperturbed counterpart. One can thus choose the dominant electron transfer pathway. The findings deliver a new opportunity for precise perturbative control of electronic energy propagation in molecular devices. Main TextControlling the function of future advanced materials demands a profound understanding of energymatter interactions in molecular systems at the quantum level. 1 There is a growing consensus that energy-and electron-transfer processes occurring far away from equilibrium in condensed-phase systems on femto-to-picosecond timescales do not conform to the Born-Oppenheimer approximation. Indeed, nuclear and electronic wave functions often strongly interact with each other, leading to exotic phenomena whereby vibrational motion can mediate and dictate the rate and efficiency of electronic transitions. [2][3][4][5] With overwhelming evidence that nuclear-electronic (vibronic) interactions play a crucial role in a broad range of systems, including light harvesting and conversion in photosynthetic organisms, 6-11 this phenomenon represents a tremendous opportunity to acquire deeper knowledge and control over the structural traits that govern molecular function and reactivity.Recent efforts led by Rubtsov et al.,12,13 Bakulin et al., 14 and our group 15,16 have shown that one way to experimentally exploit vibronic coupling to modulate molecular function is to introduce targeted vibrational excitation along specific reaction co-ordinates using ultrafast mid-infrared (IR) pulses. This approach enables promoting or suppressing electronic transitions, notably photo-induced electron transfer (ET), an elementary process that pervades the natural world. Although the demonstrated excited state modulations have been remarkably efficient, up to 100% suppression in one case, 15 predictive and directive control of electron transfer in the condensed phase has not been achieved yet.

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Section: Methodsmentioning

confidence: 99%

Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation

et al. 2017

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“…The experimental setups and procedures used for TEAS and TVAS measurements have been described previously, [28][29][30][31][32] therefore only details specific to the present study are provided here.…”

Section: Methodsmentioning

confidence: 99%

“…We estimate the concentration of the QS-MMA radical in the probed sample volume to be 0.30 mM under our experimental conditions, using a pump energy of 200 nJ/pulse, pump beam diameter of 100 μm, 28,31 sample pathlength of 100 μm, optical density of QSSQ of 0.5 OD, and a quantum yield for the survival of the two QS radicals of 31% (Table S1). The concentration of molecular oxygen in aerated CDCl3 solution is 2.4 mM assuming the solubility of molecular oxygen in CDCl3 is the same as CHCl3.…”

Section: Please Do Not Adjust Marginsmentioning

confidence: 99%

Femtosecond to microsecond observation of the photochemical reaction of 1,2-di(quinolin-2-yl)disulfide with methyl methacrylate

Koyama

Donaldson

Orr-Ewing

2017

Phys. Chem. Chem. Phys.

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“…Detailed descriptions of the laser-based instruments and the sample preparation and handling procedures are presented elsewhere, [58][59][60] and we provide only a brief summary here. Grade) before use.…”

Section: Methodsmentioning

confidence: 99%

Recombination, Solvation and Reaction of CN Radicals Following Ultraviolet Photolysis of ICN in Organic Solvents

Coulter¹,

Grubb²,

Koyama³

et al. 2015

J. Phys. Chem. A

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Ultra: A Unique Instrument for Time-Resolved Spectroscopy

Cited by 175 publications

References 35 publications

Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation

Directing the path of light-induced electron transfer at a molecular fork using vibrational excitation

Femtosecond to microsecond observation of the photochemical reaction of 1,2-di(quinolin-2-yl)disulfide with methyl methacrylate

Recombination, Solvation and Reaction of CN Radicals Following Ultraviolet Photolysis of ICN in Organic Solvents

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