Electronic spectrum of the amino acid tryptophan cooled in a supersonic molecular beam

Rizzo, Thomas R.; Park, Young D.; Peteanu, Linda A.; Levy, Donald H.

doi:10.1063/1.449009

Cited by 111 publications

(95 citation statements)

References 20 publications

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“…2, all display synconformations. It should be noted that while conformers (2a) and (2b) have been observed for the bare molecule, 1,5,19 conformers (7a) and (7b) have not.…”

Section: 19mentioning

confidence: 99%

“…4,5 The tryptophan molecule accommodates a flexible side chain which adopts at least six energetically low-lying conformations: 1,5 water molecules might bind to any of these at a number of alternative sites. Bound water molecules might select particularly favourable conformers but they might also change the preferred molecular conformation(s), to include perhaps, conformers that are not populated in the bare amino acid.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Hydrated complexes of tryptophan: ion dip infrared spectroscopy in the ‘molecular fingerprint’ region, 100–2000 cm⁻¹

Çarçabal¹,

Kroemer

Snoek³

et al. 2004

Phys. Chem. Chem. Phys.

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The infrared spectra of hydrated complexes of tryptophan have been recorded in the gas phase over the range 160-800 cm À1 using double resonance IR-UV ion dip spectroscopy. Despite the problems arising from severe UV spectral overlap of unresolved resonances, the IR measurements, combined with new DFT and ab initio calculations have allowed a re-assessment of the spectral assignments proposed in an earlier combined near-infrared/quantum computational investigation [L. C. Snoek, R. T. Kroemer and J. P. Simons, Phys. Chem. Chem. Phys. 2002Phys. , 4, 2130. It has reinforced the conclusion that hydration leads to conformational restructuring and also served to focus attention on the information that can be provided by spectroscopic measurements obtained in the mid and far IR.

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“…2, all display synconformations. It should be noted that while conformers (2a) and (2b) have been observed for the bare molecule, 1,5,19 conformers (7a) and (7b) have not.…”

Section: 19mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrated complexes of tryptophan: ion dip infrared spectroscopy in the ‘molecular fingerprint’ region, 100–2000 cm⁻¹

Çarçabal¹,

Kroemer

Snoek³

et al. 2004

Phys. Chem. Chem. Phys.

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“…In many cases, the individual conformers are identified via their different electronic spectra. 14,15 Structural information on the individual conformers can be deduced from, for instance, multiple-resonance techniques, which yield conformer-specific infrared spectra, 16,17 from the different angles between vibrational transition moments and the permanent dipole moments of oriented molecules,…”

Section: -12mentioning

confidence: 99%

Manipulating the Motion of Complex Molecules: Deflection, Focusing, and Deceleration of Molecular Beams for Quantum‐State and Conformer Selection

Küpper

Filsinger

Meijer

et al. 2012

Methods in Physical Chemistry

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Method summary Acronyms• effective dipole moment (µ eff )• low-field seeking (lfs) state• high-field seeking (hfs) state • Alternating gradient (AG) focusing• photo-multiplier tube (PMT)• transition state (TS) Strengths of technique• allows to spatially separate molecules in different quantum states, including isomers of complex molecules• versatile -DC field techniques can be applied to all polar molecules, AC field techniques to all polarizable molecules (= all molecules)• quantum-state specific interaction -can, in principle, be used to separate all kinds of isomers• determination of rotational, vibrational, and electronic properties -including dipole moments and polarizabilities -of single isomers of complex molecules• allows for detailed investigations of stereochemical dynamics• allows to separate molecular ensembles from seedgas, avoiding background in various scattering experiments Limitations• translations of non-polar molecules can -for practical purposes -not be manipulated by dc electric fields• no ultracold samples (µK or below) produced so far * This chapter is largely based on parts of reference 1. † Email: jochen.kuepper@cfel.de 1 2 Controlled moleculesChemists have long been dreaming of ultimately controlling all aspects of chemical reactions. Empirically, vast progress has been made over the last centuries using increasingly sophisticated techniques to dictate the path and outcome of chemical reactions. However, in all these approaches external parameters are used to (classically) shift statistical outcomes one way or another. Recently, the field of cold and ultracold chemistry has started to provide a glimpse at a new level of control, where full quantum-mechanical control can be obtained. So far this has been demonstrated for very specific small reactions systems, i. e., for reactions of alkali dimers with alkali atoms 2,3 or with each other, including the observation of stereochemical effects. 4 In these experiments molecules are prepared at low temperatures and specific quantum states starting from ultracold ensembles oftypically alkali -atoms, which is the limiting factor to the possible complexity and versatility of these methods. Alternatively, cold collisions of small molecules, i. e., OH radicals, with rare gas atoms at arbitrarily low collision energies have been investigated. 5,6 In this chapter we will present the available methods to gain control over the motion and the quantum-state populations over complex molecules (albeit at a lower level). These methods could enable a new level of detail in the study and control of chemical reactions for a large variety of molecules. Moreover, the prepared samples of controlled molecules are useful in a wide variety of experiments, ranging from the taking of actual photographs of the molecules -and their inherent or induced dynamics -using ultrafast X-ray or electron diffraction over, for example, photoelectron distributions and high-harmonic generation to investigations of attosecond electron dynamics and charge migration. 7 These experiments...

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“…However, even at low rotational temperatures of 1 K, which can routinely be achieved using supersonic expansions, large molecules can still remain in multiple conformations within the beam 1 . Similarly the production of molecular clusters in a beam source does not result in a single species, but rather in the formation of a "cluster soup", containing many different cluster stoichiometries, as well as remaining pure parent molecules.…”

Section: Introductionmentioning

confidence: 99%

“…Polar molecules experience a force inside an inhomogenous electric field (E) due to the spatial differences in potential energy. This force is dependent on the effective dipole moment, μ eff , of the molecule and can be evaluated as (1) As different molecular conformers typically posses different dipole moments and differing numbers of solvent molecules within a cluster lead to different cluster masses and dipole moments, these species will experience a different acceleration in the presence of a strong inhomogeneous electric field. The resulting Stark effect force from an inhomogeneous electric field can therefore be used for the separation of conformers and quantum states 22 .…”

Section: Introductionmentioning

confidence: 99%

Spatial Separation of Molecular Conformers and Clusters

Horke

Trippel

Chang

et al. 2014

JoVE

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Gas-phase molecular physics and physical chemistry experiments commonly use supersonic expansions through pulsed valves for the production of cold molecular beams. However, these beams often contain multiple conformers and clusters, even at low rotational temperatures. We present an experimental methodology that allows the spatial separation of these constituent parts of a molecular beam expansion. Using an electric deflector the beam is separated by its mass-to-dipole moment ratio, analogous to a bender or an electric sector mass spectrometer spatially dispersing charged molecules on the basis of their mass-to-charge ratio. This deflector exploits the Stark effect in an inhomogeneous electric field and allows the separation of individual species of polar neutral molecules and clusters. It furthermore allows the selection of the coldest part of a molecular beam, as low-energy rotational quantum states generally experience the largest deflection. Different structural isomers (conformers) of a species can be separated due to the different arrangement of functional groups, which leads to distinct dipole moments. These are exploited by the electrostatic deflector for the production of a conformationally pure sample from a molecular beam. Similarly, specific cluster stoichiometries can be selected, as the mass and dipole moment of a given cluster depends on the degree of solvation around the parent molecule. This allows experiments on specific cluster sizes and structures, enabling the systematic study of solvation of neutral molecules. Video LinkThe video component of this article can be found at

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Electronic spectrum of the amino acid tryptophan cooled in a supersonic molecular beam

Cited by 111 publications

References 20 publications

Hydrated complexes of tryptophan: ion dip infrared spectroscopy in the ‘molecular fingerprint’ region, 100–2000 cm⁻¹

Hydrated complexes of tryptophan: ion dip infrared spectroscopy in the ‘molecular fingerprint’ region, 100–2000 cm⁻¹

Manipulating the Motion of Complex Molecules: Deflection, Focusing, and Deceleration of Molecular Beams for Quantum‐State and Conformer Selection

Spatial Separation of Molecular Conformers and Clusters

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Electronic spectrum of the amino acid tryptophan cooled in a supersonic molecular beam

Cited by 111 publications

References 20 publications

Hydrated complexes of tryptophan: ion dip infrared spectroscopy in the ‘molecular fingerprint’ region, 100–2000 cm−1

Hydrated complexes of tryptophan: ion dip infrared spectroscopy in the ‘molecular fingerprint’ region, 100–2000 cm−1

Manipulating the Motion of Complex Molecules: Deflection, Focusing, and Deceleration of Molecular Beams for Quantum‐State and Conformer Selection

Spatial Separation of Molecular Conformers and Clusters

Contact Info

Product

Resources

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Hydrated complexes of tryptophan: ion dip infrared spectroscopy in the ‘molecular fingerprint’ region, 100–2000 cm⁻¹

Hydrated complexes of tryptophan: ion dip infrared spectroscopy in the ‘molecular fingerprint’ region, 100–2000 cm⁻¹