A novel experimental system of high stability and lifetime for the laser-desorption of biomolecules

Taherkhani, Mehran; Riese, Mikko; Benyezzar, Med; Müller‐Dethlefs, Klaus

doi:10.1063/1.3373977

Cited by 6 publications

(15 citation statements)

References 21 publications

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“…20,27 Briefly, the experiment consists of a home-built vacuum system 28 and a Nd:YAG (Continuum Minilite II) laser system for the desorption and two frequency doubled dye lasers (Radiant Narrowscan) synchronously pumped by a Nd:YAG laser (Continuum 8020…”

Section: Methodsmentioning

confidence: 99%

“…20 This long sample lifetime of above one month at the laser desorption repetition rate of 20 Hz has been achieved by optimizing cylindrical sample rods (1:1 weight ratio graphite/Tryptophan, 3 mm diameter and 6 mm length) from which the substance is laser-desorbed. Furthermore, the signal stability and signal-to-noise ratio has been very significantly improved by averaging the signal over the entire sample rod surface.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the signal stability and signal-to-noise ratio has been very significantly improved by averaging the signal over the entire sample rod surface. 20 This was achieved by synchronizing the data acquisition with the rotation of the sample rod. This system has been already successfully tested on Trp recording the Resonance-Enhanced Two-Photon Ionization, R2PI (one-colour and twocolour) spectra 20 with a resolution quality comparable to those obtained previously by Piuzzi et al 21 In the present work, this laser desorption system 20 was used to extend the spectroscopic investigation of Trp towards cationic states by employing PIE and MATI spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

“…20 This was achieved by synchronizing the data acquisition with the rotation of the sample rod. This system has been already successfully tested on Trp recording the Resonance-Enhanced Two-Photon Ionization, R2PI (one-colour and twocolour) spectra 20 with a resolution quality comparable to those obtained previously by Piuzzi et al 21 In the present work, this laser desorption system 20 was used to extend the spectroscopic investigation of Trp towards cationic states by employing PIE and MATI spectroscopy. These methods allowed the determination of an accurate value of the Trp ionisation energy (IE) albeit, surprisingly, for the excited cation D1 state and not the D0 ground state (see results section).…”

Section: Introductionmentioning

confidence: 99%

“…18,19 In contrast to these methods, producing a sufficient vapour pressure in a supersonic rare gas expansion of isolated neutral bio-molecules such as Tryptophan (Trp) for spectroscopic investigation still remains a significant challenge. 20 Since Trp is characterized by an extremely low vapour pressure and decomposes easily upon heating, carefully designed laser desorption sources are required to convey this molecule into a supersonic jet expansion cleanly and with sufficient number density to allow its spectroscopic study under molecular beam conditions.…”

Section: Introductionmentioning

confidence: 99%

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Threshold ionization spectroscopic investigation of supersonic jet-cooled, laser-desorbed Tryptophan

Taherkhani

Armentano

Černý

et al. 2016

Chemical Physics Letters

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Tryptophan (Trp) was studied by two-colour Photoionization Efficiency (PIE) and Mass Analysed Threshold Ionization (MATI) spectroscopy using a laser desorption apparatus.Conformer A of Trp was excited into the S1 state (34878cm -1 ) and the second laser was scanned around the D0 cation ground and the D1 excited state. No ionisation signal into the D0 state could be found, but a clear threshold was observed for the D1 state with an ionisation energy of 66704 ± 3 cm -1 (8.27 eV). This observation is explained in terms of the electronic configurations of the S1 and cationic states.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Threshold ionization spectroscopic investigation of supersonic jet-cooled, laser-desorbed Tryptophan

Taherkhani

Armentano

Černý

et al. 2016

Chemical Physics Letters

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Electron Correlation in Real Time

et al. 2011

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Electron correlation, caused by the interaction among electrons in a multielectron system, manifests itself in all states of matter. A complete theoretical description of interacting electrons is challenging; different approximations have been developed to describe the fundamental aspects of the correlation that drives the evolution of simple (few-electron systems in atoms/molecules) as well as complex (multielectron wave functions in atoms, molecules, and solids) systems. Electron correlation plays a key role in the relaxation mechanisms that characterize excited states of neutral or ionized atoms and molecules populated by absorption of extreme ultraviolet (XUV) or X-ray radiation. The dynamics of these states can lead to different processes such as Fano resonance and Auger decay in atoms or interatomic Coulombic decay or charge migration in molecules and clusters. Many of these relaxation mechanisms are ubiquitous in nature and characterize the interaction of complex systems, such as biomolecules, adsorbates on surfaces, and hydrogen-bonded clusters, with XUV light. These mechanisms evolve typically on the femtosecond (1 fs=10(-15) s) or sub-femtosecond timescale. The experimental availability of few-femtosecond and attosecond (1 as=10(-18) s) XUV pulses achieved in the last 10 years offers, for the first time, the opportunity to excite and probe in time these dynamics giving the possibility to trace and control multielectron processes. The generation of ultrashort XUV radiation has triggered the development and application of spectroscopy techniques that can achieve time resolution well into the attosecond domain, thereby offering information on the correlated electronic motion and on the correlation between electron and nuclear motion. A deeper understanding of how electron correlation works could have a large impact in several research fields, such as biochemistry and biology, and trigger important developments in the design and optimization of electronic devices.

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On Aromaticity of the Aromatic α-Amino Acids and Tuning of the NICS Indices to Find the Aromaticity Order

2022

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The NICS aromaticity indices of the rings in flexible phenylalanine (Phe), tryptophan (Trp), tyrosine (Tyr), and histidine (His) chiral molecules were analyzed. These molecules have several dozens of conformers, and their rings are slightly non-planar. Therefore, the population-averaged NICS pav index was defined, and the NICS scans had to be performed with respect to planes found by the least-squares routine. A rule differentiating an obverse and a reverse ring face in aromatic amino acids was formulated. The NICS scan minima corresponding to the obverse and reverse face were unequal, which prompted us to use the term ring face aromaticity/ring face tropicity. It appeared that for Phe, Trp, Tyr, and His, the reverse face has always had higher ring face aromaticity/ring face tropicity than the obverse one. Despite the NICS modifications, uncertainty about the amino acid aromaticity order remained. This motivated us to use the integral INICS index newly proposed by Stanger as well. Then, the following sequence was obtained: Trp(phenyl) > Phe > Trp(pyrrole) > His > Tyr. The juxtaposition of the INICS indices of amino acids with that of some model rings revealed a fair transferability of the values. Finally, analysis of the substituent effect on INICS demonstrated that the aromaticity of Tyr is the lowest due to the strength of the OH group π-electron-donating effect able to perturb enough the ring charge distribution and its magnetic aromaticity. The NICS calculations were executed using the ARONICS program written within the project.

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A novel experimental system of high stability and lifetime for the laser-desorption of biomolecules

Cited by 6 publications

References 21 publications

Threshold ionization spectroscopic investigation of supersonic jet-cooled, laser-desorbed Tryptophan

Threshold ionization spectroscopic investigation of supersonic jet-cooled, laser-desorbed Tryptophan

Electron Correlation in Real Time

On Aromaticity of the Aromatic α-Amino Acids and Tuning of the NICS Indices to Find the Aromaticity Order

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