Efficient cationization by Cs+ adduct ion formation in a supersonic beam

Schanen, P.; Yang, Danting; Weinkauf, R.; Schlag, E. W.

doi:10.1016/s0168-1176(97)00087-6

Cited by 3 publications

(4 citation statements)

References 75 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The protonated species is relatively more difficult to dissociate due to the need to break covalent bonds in the molecule (∼50−100 kcal/mol for a covalent bond) as opposed to losing the adduct for the M + Cs + ion complexes (∼12 kcal/ mol). 52 Overall, similar modes are observed between the two calculated spectra for [M + Cs + ] and [M + H + ], with some shifts in the position and intensity, possibly due to the lack of the delocalized charge in the neutral and the presence of the Cs + ion altering the dipole moment and its vibration-induced oscillations. The lowest-energy structure is the tautomer with N2 carrying the proton and both the carbonyl and the lone pair on N5 solvating the Cs + ion (Figure 2b, right).…”

Section: Resultsmentioning

confidence: 99%

“…The major difference between the two spectra is the absolute intensity of the spectral bands (even more striking if one takes into account that the M + Cs + spectrum has been measured with one pulse and the protonated is with two pulses). The protonated species is relatively more difficult to dissociate due to the need to break covalent bonds in the molecule (∼50–100 kcal/mol for a covalent bond) as opposed to losing the adduct for the M + Cs + ion complexes (∼12 kcal/mol) . Overall, similar modes are observed between the two calculated spectra for [M + Cs + ] and [M + H + ], with some shifts in the position and intensity, possibly due to the lack of the delocalized charge in the neutral and the presence of the Cs + ion altering the dipole moment and its vibration-induced oscillations.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

UV/Vis and IRMPD Spectroscopic Analysis of the Absorption Properties of Methylglyoxal Brown Carbon

Legaard

Thrasher

et al. 2021

ACS Earth Space Chem.

View full text Add to dashboard Cite

Brown carbon (BrC) organic molecules absorb solar radiation in the visible range and thus can influence the optical properties of atmospheric aerosol particles and cloud droplets. The absorption properties for different types of BrC can change depending on the chemical environment of the chromophores. Here, the absorption cross sections and the photo-decay rates for BrC molecules formed from methylglyoxal (MG) mixed with ammonium sulfate (MG BrC) are investigated as a function of pH. In solutions acidified to pH ∼2, MG BrC shows an ∼16 nm blueshift in peak absorbance compared to neutral solutions (pH ∼8). To probe the origins of this shift, the gas-phase infrared ion spectra of protonated and neutral imidazole carbonyl (IC), one of the main components of MG BrC, have been measured to provide insights into their structures. Excited-state energy calculations based on these structures suggest that the blueshift occurs for IC in part because protonation of the basic nitrogen in the imidazole ring inhibits conjugation with the carbonyl group attached to the ring. When the photolysis rate of a MG BrC solution that contains IC is extrapolated to atmospheric conditions, the observed blueshift at low pH increases the lifetime of the BrC mixture by ∼42%, with an estimated atmospheric lifetime of ∼82 min. These results highlight the importance of understanding how BrC photolysis rates vary across different environmental conditions.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

UV/Vis and IRMPD Spectroscopic Analysis of the Absorption Properties of Methylglyoxal Brown Carbon

Legaard

Thrasher

et al. 2021

ACS Earth Space Chem.

View full text Add to dashboard Cite

show abstract

“…The relative abundance of clusters is influenced by various parameters during their formation: the energy and focal width of the desorption laser, its peak intensity, the nozzle temperature, the time delay between desorption and cooling gas injection, the refreshing rate for the exposed molecular surface and more [29]. Also the detection parameters influence the observed cluster distribution: the ionization laser energy determines the probability for the absorption of a second photon by the already ionized complex.…”

Section: Resultsmentioning

confidence: 99%

Gas-phase formation of large neutral alkaline-earth metal tryptophan complexes

Marksteiner

Haslinger

Sclafani

et al. 2008

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

We report on the first observation of isolated large neutral metal amino acid complexes such as TrpnMek, with Me == Ca, Ba, Sr, cluster combinations covering n = 1. ..33, k = 0..2 and masses beyond 6500 u. The cluster beam is generated using UV laser desorption from a mixed powder of alkaline-earth metal salts and tryptophan inside a cluster mixing chalU1el. The particles are detected using VUV photoionization followed by time-of-flight mass spectroscopy. The enhanced stability of metal amino acid clusters over pure amino acid clusters is substantiated in molecular dynamics simulations by determining the gain in binding energy related to the inclusion of the metal atoms. . The majority of studies so far focused on the generation and use of ionic species. Our work, presented here, focuses on the gas-phase formation of neutral biomolecular clusters as did already some very early studies in the field [1]. Such experiments are often motivated by the desire to better identify the role of solvation and desolvation for the relative importance of various binding forces in organic clusters and molecules [5].The particle's neutrality is also an important criterion in efforts to establish new beam methods for quantum interferometry with molecular matter waves [6-9] as well as for precision metrology on large molecules [10][11][12]. Neutral molecules are much better isolated from any electromagnetic environment and they may therefore propagate coherently, without noticeable perturbation, even in a rather noisy field environment.Biomolecular clusters are exciting study objects for future matter wave experiments as they permit one to scale the mass in well-defined steps, while at the same time changing the internal properties in an intriguing way: the number of possible conformations as well as the number of allowed configurational and vibrational transitions scales exponentially with the size of the cluster [13], and it is still an open question how this will affect de Broglie interferometry [14], which formally considers only the center of mass motion alone. (19]. But it has still remained a challenge to find reproducible methods for photoionizing biomolecules and complexes with masses exceeding 3000 u [17,20,21].The formation and photo-detection of small amino acid [22] and nucleotide clusters [23], both hydrated and solvent-free, were already reported for objects up to 1400 u. Ultracold small bioclusters can be formed by pick-up in helium nano-droplets [24]. Complexes formed between metal atoms and amino acids were also studied to understand their structure [25], their fragmentation pathways [26,27], and metal ion affinities [28].Here we extend these investigations to much larger organometallic complexes composed of up to more than 30 tryptophan molecules with masses exceeding 6500 u, that can still be detected using VUV photoionization and time-of-flight mass spectrometry. ExperimentalWe generate the molecular macroclusters using pulsed laser evaporation and collisional cooling: the pulsed beam of aNd:YAG laser (Quantel...

show abstract

“…charge control of biomolecules in the gas phase is relevant for molecular trapping, 7 , 8 optical 9 and photo-electron spectroscopy, 10 , 11 as well as for electron or femto-second X-ray diffraction. 12 , 13 Several methods for charge manipulation have been studied in the past, such as atomic collisions, 14 chemical reactions, 15 and low-energy electron attachment. 16 …”

Section: Introductionmentioning

confidence: 99%