FG Lasermolekülspektroskopie und Umweltphysik

21 Items

Recent Submissions
Vibronic optical spectroscopy of cryogenic flavin ions: the O2+ and N1 tautomers of protonated lumiflavin

Müller, David ; Dopfer, Otto (2020-08-04)

Flavins are key compounds in many photochemical and photophysical processes used by nature, because their optical properties strongly depend on the (de-)protonation site and solvation. Herein, we present the vibronic optical spectrum of protonated lumiflavin (H+LF), the parent molecule of the flavin family, obtained by visible photodissociation (VISPD) spectroscopy in a cryogenic ion trap. By c...

Spectroscopic identification of fragment ions of DNA/RNA building blocks: the case of pyrimidine

Chatterjee, Kuntal ; Dopfer, Otto (2020-07-07)

Pyrimidine (Pym, 1,3-diazine, 1,3-diazabenzene) is an important N-heterocyclic building block of nucleobases. Understanding the structures of its fragment and precursor ions provides insight into its prebiotic and abiotic synthetic route. The long-standing controversial debate about the structures of the primary fragment ions of the Pym+ cation (C4H4N2+, m/z 80) resulting from loss of HCN, C3H3...

Microhydration of protonated biomolecular building blocks: protonated pyrimidine

Chatterjee, Kuntal ; Dopfer, Otto (2020-05-27)

Protonation and hydration of biomolecules govern their structure, conformation, and function. Herein, we explore the microhydration structure in mass-selected protonated pyrimidine–water clusters (H+Pym–Wn, n = 1–4) by a combination of infrared photodissociation spectroscopy (IRPD) between 2450 and 3900 cm−1 and density functional theory (DFT) calculations at the dispersion-corrected B3LYP-D3/a...

Intracluster proton transfer in protonated benzonitrile–(H2O)n≤6 nanoclusters: hydrated hydronium core for n ≥ 2

Chatterjee, Kuntal ; Dopfer, Otto (2019-10-31)

Protonation and hydration of aromatic hydrocarbon molecules and their derivatives play a key role in many biological and chemical processes. The recent detection of benzonitrile (BN, cyanobenzene, C6H5CN) in the interstellar medium suggests the existence of its protonated form (H+BN) in both the gas phase and in or on ice grains. Herein, we analyze the vibrational signatures of size-selected pr...

Microhydration Structures of Protonated Oxazole

Chatterjee, Kuntal ; Dopfer, Otto (2019-08-22)

The initial microhydration structures of the protonated pharmaceutical building block oxazole (Ox), H+Ox-Wn≤4, are determined by infrared photodissociation (IRPD) spectroscopy combined with quantum chemical dispersion-corrected density functional theory calculations (B3LYP-D3/aug-cc-pVTZ). Protonation of Ox, achieved by chemical ionization in a H2-containing plasma, occurs at the most basic N a...

Unraveling the protonation site of oxazole and solvation with hydrophobic ligands by infrared photodissociation spectroscopy

Chatterjee, Kuntal ; Dopfer, Otto (2019-01-19)

Protonation and solvation of heterocyclic aromatic building blocks control the structure and function of many biological macromolecules. Herein the infrared photodissociation (IRPD) spectra of protonated oxazole (H+Ox) microsolvated by nonpolar and quadrupolar ligands, H+Ox-Ln with L = Ar (n = 1–2) and L = N2 (n = 1–4), are analyzed by density functional theory calculations at the dispersion-co...

Effect of alkali ions on optical properties of flavins: vibronic spectra of cryogenic M+lumiflavin complexes (M = Li–Cs)

Müller, David ; Nieto, Pablo ; Miyazaki, Mitsuhiko ; Dopfer, Otto (2019-01-07)

Flavin compounds are frequently used by nature in photochemical processes because of their unique optical properties which can be strongly modulated by the surrounding environment such as solvation or coordination with metal ions. Herein, we employ vibronic photodissociation spectroscopy of cryogenic M+LF complexes composed of lumiflavin (LF, C13H12N4O2), the parent molecule of the flavin famil...

Microhydration of protonated 5-hydroxyindole revealed by infrared spectroscopy

Klyne, Johanna ; Dopfer, Otto (2019-01-08)

Controlled microsolvation of protonated aromatic biomolecules with water is fundamental to understand proton transfer reactions in aqueous environments. We measured infrared photodissociation (IRPD) spectra of mass-selected microhydrates of protonated 5-hydroxyindole (5HIH+–Wn, W = H2O, n = 1–3) in the OH and NH stretch ranges (2700–3800 cm−1), which are sensitive to the spectroscopic character...

Spectroscopy of protonated aromatic and chiral biomolecules

Klyne, Johanna Karin (2019)

Characterizing the interactions in clusters of protonated aromatic and chiral biomolecules is essential to understand their chemical reactions and molecular recognition. In this thesis, three prototypical biomolecular building blocks are investigated by sophisticated infrared (IR) and ultraviolet (UV) laser spectroscopic methods and density functional theory (DFT) calculations. First, the proto...

Spektroskopie der Neurotransmitter Tryptamin und Phenylethylamin

Schütz, Markus (2018)

The maintenance of bodily functions in living beings is determined by a variety of biochemical processes, collectively referred to as metabolism. Molecular spectroscopy can be used to study processes at the molecular level and to draw conclusions about interactions and possible functionalities. The signal transmission between chemical neurons is based inter alia on the binding of a neurotransmi...

Spektroskopie an silizium- und kohlenstoffhaltigen Clustern: Dotierung und Hybride

Savoca, Marco (2018)

Silicon oxides and silicon carbides are not only in the focus of the semiconductor industry and relevant for the development of new materials from clusters and nanoparticles, they are also of interest in the chemistry of the interstellar medium. In this context, the availability of experimental data regarding structure of doped silicon clusters is an essential basis for exploring and controllin...

Nature of the interaction between rare gas atoms and transition metal doped silicon clusters: the role of shielding effects

Vu Thi Ngan ; Janssens, Ewald ; Claes, Pieterjan ; Fielicke, André ; Minh Tho Nguyen ; Lievens, Peter (2015)

Mass spectrometry experiments show an exceptionally weak bonding between Si7Mn+ and rare gas atoms as compared to other exohedrally transition metal (TM) doped silicon clusters and other SinMn+ (n = 5-10) sizes. The Si7Mn+ cluster does not form Ar complexes and the observed fraction of Xe complexes is low. The interaction of two cluster series, SinMn+ (n = 6-10) and Si7TM+ (TM = Cr, Mn, Cu, and...

Vibrational spectra and structures of SinC clusters (n=3-8)

Nguyen Xuan Truong ; Savoca, Marco ; Harding, Dan J. ; Fielicke, André ; Dopfer, Otto (2015)

The effects of doping bare silicon clusters with carbon on their physical properties are of fundamental interest for the chemistry of the interstellar medium and the development of novel nanostructures in materials science. Carbon-doped silicon clusters (SinC, n = 3-8) are characterized in the gas phase with infrared-ultraviolet two-color ionization (IR-UV2CI) spectroscopy, mass spectrometry, a...

Diastereo-specific conformational properties of neutral, protonated and radical cation forms of (1R,2S)-cis- and (1R,2R)-trans-amino-indanol by gas phase spectroscopy

Bouchet, Aude ; Klyne, Johanna ; Piani, Giovanni ; Dopfer, Otto ; Zehnacker, Anne (2015)

Chirality effects on the intramolecular interactions strongly depend on the charge and protonation states. Here, the influence of chirality on the structure of the neutral, protonated, and radical cation forms of (1R,2S)-cis- and (1R,2R)-trans-1-amino-2-indanol diastereomers, prototypical molecules with two chiral centers, is investigated in a molecular beam by laser spectroscopy coupled with q...

IR spectrum of the protonated neurotransmitter 2-phenylethylamine: dispersion and anharmonicity of the NH3+-pi interaction

Bouchet, Aude ; Schütz, Markus ; Chiavarino, Barbara ; Crestoni, Maria Elisa ; Fornarini, Simonetta ; Dopfer, Otto (2015)

The structure and dynamics of the highly flexible side chain of (protonated) phenylethylamino neurotransmitters are essential for their function. The geometric, vibrational, and energetic properties of the protonated neutrotransmitter 2-phenylethylamine (H(+)PEA) are characterized in the N-H stretch range by infrared photodissociation (IRPD) spectroscopy of cold ions using rare gas tagging (Rg ...

Single water solvation dynamics in the 4-aminobenzonitrile-water cluster cation revealed by picosecond time-resolved infrared spectroscopy

Miyazaki, Mitsuhiko ; Nakamura, Takashi ; Wohlgemuth, Matthias ; Mitrić, Roland ; Dopfer, Otto ; Fujii, Masaaki (2015)

The dynamics of a solvent is important for many chemical and biological processes. Here, the migration dynamics of a single water molecule is triggered by the photoionization of the 4-aminobenzonitrile-water (4ABN-W) cluster and monitored in real time by picosecond time-resolved IR (ps TRIR) spectroscopy. In the neutral cluster, water is hydrogen-bonded to the CN group. When this CN-bound clust...

Mass analyzed threshold ionization detected infrared spectroscopy: isomerization activity of the phenol-Ar cluster near the ionization threshold

Miyazaki, Mitsuhiko ; Yoshikawa, Shunpei ; Michels, François ; Misawa, Kentaro ; Ishiuchi, Shun-ichi ; Sakai, Makoto ; Dopfer, Otto ; Müller-Dethlefs, Klaus ; Fujii, Masaaki (2015)

The structure of the phenol-argon cluster (PhOH-Ar) in high-n Rydberg states is investigated by the newly developed technique of mass analyzed threshold ionization detected infrared (MATI-IR) spectroscopy. This method selectively measures IR spectra of molecular clusters in very high-n Rydberg states (n > 100) utilized in zero kinetic energy (ZEKE) photoelectron and MATI spectroscopy, whose ion...

Photoionization-induced pi <-> H site switching dynamics in phenol(+)-Rg (Rg = Ar, Kr) dimers probed by picosecond time-resolved infrared spectroscopy

Miyazaki, Mitsuhiko ; Sakata, Yuri ; Schütz, Markus ; Dopfer, Otto ; Fujii, Masaaki (2016)

The ionization-induced pi <-> H site switching reaction in phenol(+)-Rg (PhOH+-Rg) dimers with Rg = Ar and Kr is traced in real time by picosecond time-resolved infrared (ps-TRIR) spectroscopy. The ps-TRIR spectra show the prompt appearance of the non-vanishing free OH stretching band upon resonant photoionization of the pi-bound neutral clusters, and the delayed appearance of the hydrogen-bond...

Structural motifs of 2-(2-fluoro-phenyl)-ethylamine conformers

Mayorkas, Nitzan ; Sachs, Hanan ; Schütz, Markus ; Ishiuchi, Shun-ichi ; Fujii, Masaaki ; Dopfer, Otto ; Bar, Ilana (2016)

Vibronic and vibrational spectra of 2-(2-fluoro-phenyl)-ethylamine (2-FPEA) conformers were measured in a molecular beam by resonant two-photon ionization (R2PI), ultraviolet-ultraviolet hole burning (UV-UV HB) spectroscopy, and ionization-loss stimulated Raman spectroscopy (ILSRS). The measured ILSR spectral signatures in the survey spectra of the amino group region and in the broad spectral r...

Structural determination of niobium-doped silicon clusters by far-infrared spectroscopy and theory

Li, Xiaojun ; Claes, Pieterjan ; Härtelt, Marko ; Lievens, Peter ; Janssens, Ewald ; Fielicke, André (2016)

In this work, the structures of cationic SinNb+ (n = 4-12) clusters are determined using the combination of infrared multiple photon dissociation (IR-MPD) and density functional theory (DFT) calculations. The experimental IR-MPD spectra of the argon complexes of SinNb+ are assigned by comparison to the calculated IR spectra of low-energy structures of SinNb+ that are identified using the stocha...