Do large molecules ionize?

Schlag, E. W.; Grotemeyer, Jürgen; Levine, R. D.

doi:10.1016/0009-2614(92)85185-d

Cited by 101 publications

(72 citation statements)

References 36 publications

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“…Experimental studies of peptides were used to argue that molecules larger than ¾2000 Da cannot be photoionized by SPI or MPI. 107 Subsequent experimental work argued that there is no apparent limit on the size of molecule that can be photoionized by SPI or MPI. 108 When laser desorbed polymers were subjected to supersonic cooling, a 4000 Da limit was obtained by SPI and a 7000 Da limit was obtained by MPI (albeit for different classes of polymers).…”

Section: Internal Energy Of Desorbed Molecules and Fragmentation Durimentioning

confidence: 99%

Surface mass spectrometry of molecular species

et al. 1999

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Section: Internal Energy Of Desorbed Molecules and Fragmentation Durimentioning

confidence: 99%

Surface mass spectrometry of molecular species

et al. 1999

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“…(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].…”

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confidence: 99%

“…(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].…”

mentioning

confidence: 99%

“…Ionization methods used in the past have been as diverse as the molecules· under investigation: UV multi-photon ionization [1] was in competition with single-photon ionization using VUV lamps [IS], VUV lasers [16], dye tagging of molecules [17], femtosecond ionization (18], or even thermionic emission of electrons (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].…”

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confidence: 99%

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

Marksteiner

Haslinger

Sclafani

et al. 2008

J. Am. Soc. Mass Spectrom.

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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...

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“…SPI has been observed for gaseous molecular species produced during laser desorption, evaporation, thermal desorption, and keV ion sputtering [6 -21]. Laser desorption combined with various laser postionization schemes have been studied for many years and is well established [8,9,12,[22][23][24], although not as popular as other desorption/ ionization schemes. However, the recent expansion in the use of commercial atmospheric pressure photoionization sources [17] indicates the promise of vacuum ultraviolet (VUV) photoionization in vacuum for mass spectrometric applications.…”

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confidence: 99%

7.87 eV laser desorption postionization mass spectrometry of adsorbed and covalently bound bisphenol a diglycidyl methacrylate

Zhou

Akhmetov

et al. 2007

J. Am. Soc. Mass Spectrom.

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Bisphenol A diglycidyl methacrylate (Bis-GMA) was adsorbed onto or covalently bound to a porous silicon oxide surface. Laser desorption 10.5 eV postionization mass spectrometry (LDPI-MS) was previously demonstrated for surface analysis of adsorbed and surface bound Bis-GMA, but signal to noise levels were low and ion fragmentation was extensive. 7.87 eV postionization using the fluorine laser was demonstrated here for Bis-GMA. However, signal levels remained low for LDPI-MS of Bis-GMA as its ionization potential (IP) was only ϳ7.8 eV, near threshold for single photon ionization by the 7.87 eV fluorine laser. It is known that aromatic tagging of molecular analytes can lower the overall IP of the tagged molecular complex, allowing 7.87 eV single photon ionization. Therefore, Bis-GMA was also derivatized with several tags whose IPs were either below or above 7.87 eV: the tag with an IP below 7.87 eV enhanced single photon ionization while the tags with higher IPs did not. However, signal intensities were enhanced by resonant laser desorption for two of the derivatized Bis-GMAs. Intact ions of Bis-GMA and its derivatives were generally observed by 7.87 eV LDPI-MS, consistent with the formation of ions with relatively little internal energy upon threshold single photon

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Do large molecules ionize?

Cited by 101 publications

References 36 publications

Surface mass spectrometry of molecular species

Surface mass spectrometry of molecular species

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

7.87 eV laser desorption postionization mass spectrometry of adsorbed and covalently bound bisphenol a diglycidyl methacrylate

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