Femtosecond Dynamics of Isolated Phenylcarbenes

Noller, Bastian; Poisson, L.; Maksimenka, Raman; Fischer, Ingo; Mestdagh, J. M.

doi:10.1021/ja804133c

Cited by 18 publications

(30 citation statements)

References 12 publications

(21 reference statements)

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“…Recently, we extended this work to carbenes and gained significant insight into the excited-state dynamics of phenylcarbenes. 13 Here, we extend this work to the excited state dynamics of propadienylidene, a singlet carbene with C 2v symmetry and an X 1 A 1 ground state. Its structure is depicted in Fig.…”

Section: Introductionmentioning

confidence: 89%

Excited-state lifetime of propadienylidene, l-C3H2

Noller

Margraf

Schröter

et al. 2009

Phys. Chem. Chem. Phys.

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The excited-state dynamics of the singlet carbene propadienylidene, l-C(3)H(2), were investigated by femtosecond time-resolved photoionisation. The carbene was excited into the C (1)A(1) state with 250 nm pulses and the subsequent excited state dynamics were probed by multiphoton ionization with 800 nm pulses. The lifetime of the C (1)A(1) state was determined to be 70 fs. In agreement with recent nanosecond experiments, we assume that the carbene deactivates to the electronic ground state where it subsequently dissociates. Since propadienylidene was generated from 3-bromo-1-iodopropyne, two further radical intermediates were studied, IC(3)H(2) and C(3)H(2)Br. For both species, an ultrafast excited state decay was observed with an upper limit of 40 fs for the respective lifetimes.

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Section: Introductionmentioning

confidence: 89%

Excited-state lifetime of propadienylidene, l-C3H2

Noller

Margraf

Schröter

et al. 2009

Phys. Chem. Chem. Phys.

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confidence: 99%

Photoelectron angular distributions from strong-field ionization of oriented molecules

et al. 2010

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The combination of photoelectron spectroscopy and ultrafast light sources is on track to set new standards for detailed interrogation of dynamics and reactivity of molecules [1][2][3][4][5][6][7]. A crucial prerequisite for further progress is the ability to not only detect the electron kinetic energy, as done in traditional photoelectron spectroscopy, but also the photoelectron angular distributions (PADs) in the molecular frame [1,4,5,[7][8][9][10]. Until recently the only method relied on determining the orientation of the molecular frame after ionization [1,[11][12][13].This requires that ionization leads to fragmentation thereby limiting both the species and the specific processes that can be studied. An attractive alternative is to fix the molecular frame prior to ionization. The only demonstrations hitherto involved aligned small linear unpolar molecules [4,5,8]. A decisive milestone is extension to the general class of polar molecules. Here carbonylsulfide (OCS) and benzonitrile (C 7 H 5 N) molecules, fixed in space by combined laser and electrostatic fields, are ionized with intense, circularly polarized, 30 femtosecond laser pulses. For 1-dimensionally oriented OCS the molecular frame PADs exhibit pronounced anisotropies, perpendicular to the fixed permanent dipole moment, that are absent in PADs from randomly oriented molecules.For 3-dimensionally oriented C 7 H 5 N additional striking structures appear due to suppression of electron emission in nodal planes of the fixed electronic orbitals. Our theoretical analysis, relying on tunneling ionization theory [14,15], shows that the PADs reflect nodal planes, permanent dipole moments and polarizabilities of both the neutral molecule and its cation. The calculated results are exponentially sensitive to changes in these molecular properties thereby pointing to exciting opportunities for time-resolved probing of valence electrons dynamics by intense circularly polarized pulses. Molecular frame PADs from oriented molecules will prove important in other contexts notably in emerging free-electron-laser studies where localized inner shell electrons are knocked off by x-ray pulses.Experimentally a target of adiabatically aligned and oriented molecules is created by the combined action of a 10 nanosecond laser pulse and a weak static electric field [16,17].Here alignment refers to confinement of molecule-fixed axes along laboratory fixed axes, and orientation refers to the molecular dipole moment pointing in a particular direction 2 [18]. Before reaching the interaction point with the laser pulses and the static field the molecules are selected in the lowest-lying rotational quantum states by an electrostatic deflector [19]. Hereby alignment and orientation is optimized, which is crucial for observation of the molecular frame PAD effects discussed next. The degree of alignment and orientation is initially measured by Coulomb exploding the molecules using an intense femtosecond (fs) probe laser pulse ( Supplementary Information, SI).For the PAD experiments a circul...

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“…The second species of interest was trifluoromethylphenyl carbene (TFPC), generated from trifluoromethylphenyl diazirines according to the upper trace of Figure 2. We recently investigated the femtosecond dynamics15, 16 as well as the photoionization17 of several phenylcarbenes PhCX in the gas phase. While the dynamics of chlorophenylcarbene (X=Cl) could be rationalized with the aid of computations, the results for TFPC were less clear cut and could not be fully understood.…”

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confidence: 99%