2 edition of Ionization and fragmentation of simple molecules found in the catalog.
Ionization and fragmentation of simple molecules
C. J Latimer
Written in English
Thesis (Ph. D.)--The Queen"s University of Belfast, 1970.
|The Physical Object|
atmospheric pressure ionization, electrospray ionization, identification, MS/MS, small molecules, structural elucidation This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in. This is the first comprehensive treatment of the interactions of atoms and molecules with charged particles, photons and laser fields. Addressing the subject from a unified viewpoint, the volume reflects our present understanding of many-particle dynamics in rearrangement and fragmentation reactions such as electron capture, target and projectile ionisation, photoabsorption and Compton.
Single ionization of simple molecules, e.g. H2, CO2, by fast charged particle impact has been studied using a reaction microscope. By measuring the momenta of the emitted electron and the recoil ionic fragment in coincidence, channel-selective low-energy electron spectra have been recorded. We discuss the ionization and fragmentation of isolated monomers and cold clusters of polycyclic aromatic hydrocarbon (PAH) molecules in collisions with keV ions in low or high ch.
The photoelectron spectra of 67 organic compounds, including paraffins, cycloparaffins, olefines, dienes, aromatic hydrocarbons, alcohols, ethers, aldehydes, ketones, and diene iron tricarbonyl complexes, have been measured, using a simple retarding‐potential grid‐type spectrometer, and the results interpreted in terms of a recently. • Molecular ion: Ion formed by addition or the removal of one or several electrons to or from the sample molecules- Electron Impact (EI-MS). M + e- M+•+ 2e-• Adduct Ion: Ion formed through interaction of two species and containing all the atoms of one of them plus one or .
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In mass spectrometry, fragmentation is the dissociation of energetically unstable molecular ions formed from passing the molecules in the ionization chamber of a mass spectrometer. The fragments of a molecule cause a unique pattern in the mass reactions are well documented over the decades and fragmentation pattern is useful to determine the molar weight and structural.
We studied the fragmentation dynamics of small molecules, as e.g. N 2 or CH 4, in collisions with slow He 2+ and Ar 3+ ions. A combination of position- and time-sensitive detectors allows the coincident measurement of the generated electrons and fragment ions as well as of those projectiles involved in a charge exchange by: The ionization and fragmentation produced in collisions of 40 MeV Ar 13+ projectiles with O 2, CO, CO 2, N 2 O and SO 2 have been identified by time-of-flight mass spectrometry.
In each case, the singly ionized molecular ion is observed to have the highest yield, while substantial yields of doubly charged molecular ions appear in the spectra for CO, CO 2 and SO by: 8.
Ionization or ionisation, is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical resulting electrically charged atom or molecule is called an tion can result from the loss of an electron after collisions with subatomic particles, collisions with other atoms, molecules.
Click here for examples of compounds listed by functional group, which demonstrate patterns which can be seen in mass spectra of compounds ionized by electron impact ionization.
Example The mass spectrum of an aldehyde gives prominent Ionization and fragmentation of simple molecules book at m/z = 59 (12%, highest value of m/z in the spectrum), 58 (85%), and 29 (%), as well as others.
Ion fragmentation of small molecules in mass spectrometry Jeevan Prasain [email protected] J. Prasain 01/19/11 Nomenclature: the main names and acronyms used in mass spectrometry • Molecular ion: Ion formed by addition or the removal of one or several electrons to or from the sample molecules-Electron Impact (EI-MS).
M + e- M+•+ 2e. The ionization and fragmentation of some organic molecules by intense femtosecond pulses are described. One of the distinctive features of femtosecond ionization is intact molecular ion formation; but is not always the case.
Therefore, this article is particularly concerned with how to produce intact molecular ions. The formation of molecular ions. When the vaporised organic sample passes into the ionisation chamber of a mass spectrometer, it is bombarded by a stream of electrons.
These electrons have a high enough energy to knock an electron off an organic molecule to form a positive ion. This ion is called the molecular ion - or sometimes the parent ion. Following are examples of compounds listed by functional group, which demonstrate patterns which can be seen in mass spectra of compounds ionized by electron impact ionization.
These examples do not provide information about the fragmentation mechanisms that cause these patterns. V Multiple ionization and fragmentation of isolated pyrene and coronene molecules in collision with ions A.
Ławicki, A. Holm, P. Rousseau, M. Capron, R. Ion pair production and their kinetic energy distribution in the charge transfer of 3–20 keV H + and He + ions with simple molecules has been studied. Multiple ionization fragmentation of SF 6 by 1 MeV protons using the triple coincidence technique has allowed the different fragmentation channels to be identified unambiguously along with the.
The ions formed by FAB were adducts to the molecule, where the adducts could be protons, sodium ions, potassium ions or ammonium ions. A variation of FAB was replacement of the atom beam with a beam of ions, typically cesium ions, which was called secondary ion mass spectrometry (SIMS).
When neutral molecules are exposed to an intense laser pulse, they can be aligned as well as ionized by the electric field of the laser (Stapelfeldt and Seideman ).The coexistence of both effects makes it difficult experimentally to extract the dependence of ionization rates on the alignment of molecules with respect to the direction of laser polarization.
Single ionization of simple molecules, e.g. H-2, CO2, by fast charged particle impact has been studied using a reaction microscope. By measuring the momenta of the emitted electron and the recoil.
Fundamentals – Ionization, Fragmentation, Chemical Reactions & Separations Data Independent Acquisition presented by Birgit Schilling (Buck Institute) on June 2, MALDI: Past and Future presented by Kermit Murray (Louisiana State University) on June 4, compounds may completely lack a visible molecular ion.
In these cases, it is critical that fragment peaks are not mistakenly identified as the molecular ion peak in order to avoid misidentification of an analyte.
Obtaining a chemical ionization spectrum can assist in correctly identifying the molecular ion. An even more powerful method to investigate mass spectral fragmentations and fragmentation pathways of molecules are ion tree experiments [–] (see Fig.
10). A data-dependent ion tree contains multiple MS 2 to MS n product ion spectra from a single molecule and represents the ultimate mass spectral fingerprint of a molecule. of ionization is increased by increasing the trap current.
The limitation in this case relates Figure Relationship between ion production and energy (electron volts) of ionizing electrons: A, threshold region, principally molecular ions produced; B, production of fragment ions becomes important; C, routine operation, mostly fragment ions.
It produces molecular ions with little or no fragmentation. Application of very strong electric field induces emission of electrons. Sample molecules in vapor phase is brought between two closely spaced electrodes in the presence of high electric field ( - V/cm) it experiences electrostatic force.
If the metal surface (anode) has proper. produce molecular ions, other techniques are very energetic and cause ions to * undergo extensive fragmentation. Although this fragmentation complicates the mass spectrum, it provides structural information for the identification of unknown compounds.
Electron Ionization. Electron Ionization (EI) is the most common ionization technique. Fragmentation (mass spectrometry) Last updated Decem In mass spectrometry, fragmentation is the dissociation of energetically unstable molecular ions formed from passing the molecules in the ionization chamber of a mass spectrometer.
The fragments of a molecule cause a unique pattern in the mass reactions are well documented over the decades and fragmentation. The Electrospray Ionization (ESI) is a soft ionization technique extensively used for production of gas phase ions (without fragmentation) of thermally labile large supramolecules.
In the present review we have described the development of Electrospray Ionization mass spectrometry (ESI-MS) during the last 25 years in the study of various.A scheme of ascorbic acid fragmentation due to electron-impact-induced ionization is suggested, and possible channels of producing the most intense fragment ions in the mass spectrum are indicated.