Splitting of the Zero Phonon Lines of Indole, 3-Methyl Indole, Tryptamine and N-Acetyl Tryptophan Amide in Helium Droplets

Lindinger, Albrecht; Lugovoj, Eugene; Toennies, J. P.; Vilesov, Andrey F.

doi:10.1524/zpch.2001.215.3.401

Cited by 38 publications

(57 citation statements)

References 41 publications

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“…Although splitting of ZPL's has been observed in many molecular systems, a complete understanding of the phenomena is still lacking. 52,[65][66][67] Analysis of the rotational band contour of the A 2 resonance of gas phase adenine is consistent with a transition involving a 1 pp* state, 14 thus corroborating its previous assignment to the 0-0 transition to the 1 L b (pp*) state. 12 In helium droplets, this transition has the largest linewidth, 12.2 cm À1 , of the observed transitions.…”

Section: Resultssupporting

confidence: 79%

Absorption spectroscopy of adenine, 9-methyladenine, and 2-aminopurine in helium nanodroplets

Smolarek

Rijs

Buma

et al. 2010

Phys. Chem. Chem. Phys.

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High-resolution absorption spectra of adenine, 9-methyladenine and 2-aminopurine in helium nanodroplets have been recorded. In contrast to molecular beam experiments, large variations in linewidths are observed for adenine and 9-methyladenine. At the same time, the spectrum of 2-aminopurine remains sharp upon solvation in helium droplets. The line broadening observed for adenine and 9-methyladenine is attributed to a significant decrease of the lifetime of the 1 L b (pp*) state and of 1 np* levels vibronically coupled to this state. The origin of the lifetime reduction is argued to be related to the increased accessibility of the 1 np*/ 1 L b (pp*) conical intersection upon solvation of these molecules in liquid helium.

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Section: Resultssupporting

confidence: 79%

Absorption spectroscopy of adenine, 9-methyladenine, and 2-aminopurine in helium nanodroplets

Smolarek

Rijs

Buma

et al. 2010

Phys. Chem. Chem. Phys.

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“…The electronic transitions to the first excited singlet states (S 1 ! S 0 ) for a number of organic molecules, such as glyoxal, [171,203] polyaromatics, [154,212,213] indoles, [214] and porphyrins [213,215] in helium droplets have been investigated. In most cases the spectra were detected by LIF except for glyoxal, naphthalene, N-acelyl tryptophan amide (NATA), and C 60 for which the depletion technique was used (Section 3.4).…”

Section: Electronic Excitation Spectramentioning

confidence: 99%

“…[154,203,213,214] In Table 4 the S 1 ! S 0 ZPL electronic origins for 16 mostly organic or biologically interesting molecules in helium droplets are listed.…”

Section: Electronic Excitation Spectramentioning

confidence: 99%

Superfluid Helium Droplets: A Uniquely Cold Nanomatrix for Molecules and Molecular Complexes

2004

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Herein, recent experiments on the spectroscopy and chemical reactions of molecules and complexes embedded in helium droplets are reviewed. In the droplets, a high spectroscopic resolution, which is comparable to the gas phase is achieved, while an isothermal low-temperature environment is maintained by evaporative cooling at T =0.37 K (4He droplets) or 0.15 K (3He droplets), lower than possible in most solid matrices. Thus the helium-droplet technique combines the benefits of both the gas phase and the classical matrix-isolation techniques. Most important, the superfluid helium facilitates binary encounters, and absorbs the released binding energy upon recombination. Thus the droplet can be viewed as an isothermal nanoscopic reactor, which isolates single molecules, clusters, or even a single reactive encounter at ultralow temperatures.

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“…As a derivative of the biologically important natural amino acid tryptophan, tryptamine has attracted considerable interest over the past three decades. 23,[31][32][33][34][35][36][37][38] Park et al were the first to record electronic spectroscopy of tryptamine with vibrational resolution under supersonic jet conditions. 23 They identified six conformers labeled as A through F. Later, with the additional information from partial rotationally resolved laser induced fluorescence ͑LIF͒ excitation spectroscopy 31,38 and triply deuterated conformers, 32 assignment of conformational structures was attempted.…”

Section: Introductionmentioning

confidence: 99%

Conformational identification of tryptamine embedded in superfluid helium droplets using electronic polarization spectroscopy

Zhang

et al. 2006

The Journal of Chemical Physics

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We report electronic polarization spectroscopy of tryptamine embedded in superfluid helium droplets. In a dc electric field, dependence of laser induced fluorescence from tryptamine on the polarization direction of the excitation laser is measured. Among the three observed major conformers A, D, and E, conformers D and E display preference for perpendicular excitation relative to the orientation field, while conformer A is insensitive to the polarization direction of the excitation laser. We attribute the behavior of conformer A to the fact that the angle between the permanent dipole and the transition dipole is close to the magic angle. Using a linear variation method, we can reproduce the polarization preference of the three conformers and determine the angle between the transition dipole and the permanent dipole. Since the side chain exerts small effect on the direction of the transition dipole in the frame of the indole chromophore, all three conformers have a common transition dipole more or less in the indole plane at an angle of approximately 60 degrees relative to the long axis of the chromophore. The orientation of the side chain, on the other hand, determines the size and direction of the permanent dipole, thereby affecting the angle between the permanent dipole and the transition dipole. For conformer D in the droplet, our results agree with the Anti(ph) structure, rather than the Anti(py) structure. Our work demonstrates that polarization spectroscopy is effective in conformational identification for molecules that contain a known chromophore. Although coupling of the electronic transition with the helium matrix is not negligible, it does not affect the direction of the transition dipole.

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Splitting of the Zero Phonon Lines of Indole, 3-Methyl Indole, Tryptamine and N-Acetyl Tryptophan Amide in Helium Droplets

Cited by 38 publications

References 41 publications

Absorption spectroscopy of adenine, 9-methyladenine, and 2-aminopurine in helium nanodroplets

Absorption spectroscopy of adenine, 9-methyladenine, and 2-aminopurine in helium nanodroplets

Superfluid Helium Droplets: A Uniquely Cold Nanomatrix for Molecules and Molecular Complexes

Conformational identification of tryptamine embedded in superfluid helium droplets using electronic polarization spectroscopy

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