Account: Multiphoton ionization mass spectrometry: principles and fields of application

2017

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The fragmentation behavior of N, N-diethylamino-substituted azobenzene derivatives is investigated by high-resolving mass spectrometry using a Fourier transform ion cyclotron resonance mass spectrometer. Former investigations by photodissociation as well as collision-induced dissociation experiments used to induce a loss of CH from the diethylamino group. The position of the additional proton in [M + H] ions is important due to the sequences of radical fragmentation reactions. Two possibilities arise. First, a charge is located at the azo group leading to a methyl radical loss. The second possibility is that the charge has been located on the aniline nitrogen of the molecule resulting in an ethyl radical loss. Only o-ethyl red has shown the overall loss of CH in a two-step radical reaction mechanism. Nevertheless, p-ethyl red and ethyl yellow have shown systematic fragmentation reactions as well. Loss of CH has not been likely regarding both these molecules. All experimental findings together with quantum chemical calculations as well as kinetic calculations support the proposed fragmentation mechanisms of the three azo dyes.

Section: Resultsmentioning

confidence: 99%

Subsequent radical fragmentation reactions of N,N-diethylamino-substituted azobenzene derivatives in a Fourier transform ion cyclotron resonance mass spectrometer using collision-induced dissociation and photodissociation

Clemen

2017

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“…This difference is easily explained through the photon processes necessary to induce the fragmentation. Following basic photophysical laws for multiphoton processes, 32,33 the number of photons can be estimated through a double-logarithmic plot of the laser power versus the measured ion intensity which results in a straight line. The slope then yields the number photons in the photophysical process, here the various fragmentations.…”

Section: Resultsmentioning

confidence: 99%

Photodissociation at Various Wavelengths: Fragmentation Studies of Oxazine 170 Using Nanosecond Laser Pulses

Gernert

2015

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The fragmentation of oxazine 170, a rhodamine-type dye, has been investigated by means of collisions and photodissociation with visible and ultraviolet radiation in a Fourier transform ion cyclotron resonance mass spectrometer. Because of an improved experimental setup, the photodissociation processes of stored ions are measured with high intensity with respect to the absorbed photons. By isotope labelling and quantum chemical calculations, the various fragmentation mechanisms are investigated. It is shown that the most important intermediate ion structure leading to the various ionic products is an even-electron azarine cation. Several new fragmentation mechanisms have been unveiled for the first time.

“…The design of the ion source allows the production of ions by two different means: resonance-enhanced multiphoton ionization (REMPI) 20 and laser-generated electron ionization (LEI). 21 In LEI mode, the laser is focused on a tantalum wire that is tensed in the first source region at a distance of 2.3 mm from the repeller.…”

Section: Simulation and Setup Of The Complete Instrumentmentioning

confidence: 99%

Design, Setup and First Results of a Miniaturized Time-of-Flight Mass Spectrometer with a Simple Reflector of a New Design

Uphoff

Muskat

2004

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A new kind of reflector with only one element has been constructed and used in a miniaturized time-of- flight mass spectrometer. Details from the simulation of the instrument with SIMION and its design are presented and discussed. The instrumental setup is displayed and some first results from measurements are presented. Laser- generated electron ionization (LEI) and resonance-enhanced multi-photon ionization (REMPI) are used for ion production. While both methods yield good mass spectra, the mass resolving power of the instrument is different for both methods. The results of the measurements are compared and discussed with respect to the design. It is found that the resolution of the new instrument is satisfactory for mass spectrometric measurements of small molecules and not limited by the reflector.