Application of laser induced photoemission electron in time-of-flight mass spectrometry

Wang, Li; Li, Haiyang; Bai, Jian‐Fei; Hua, Xiaoqing; Lu, Ruifeng

doi:10.1016/s1387-3806(98)14159-3

Cited by 7 publications

(7 citation statements)

References 18 publications

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“…Application on Monitoring Components in Discharging of SF 6 . SF 6 (IE 15.32 eV) is an important gas used in the electrical industry as a dielectric medium for high-voltage circuit breakers, switchgear, and other electrical equipment.…”

Section: Application On Monitoring Products In Pyrolysis Of Pvcmentioning

confidence: 99%

“…SF 6 (IE 15.32 eV) is an important gas used in the electrical industry as a dielectric medium for high-voltage circuit breakers, switchgear, and other electrical equipment. The impurities in SF 6 will greatly reduce its performance; thus, the monitoring of components gives a way to prevent the discharging. 36 In addition, the monitoring can also serve as an effective way for online fault detection and diagnosis in SF 6 insulated equipment, because of the characteristic products in different discharge modes.…”

Section: Application On Monitoring Products In Pyrolysis Of Pvcmentioning

confidence: 99%

“…Single photon ionization (SPI) is one of the most popular ionization methods used for online monitoring, due to its high molecular ion yield and simple spectrum interpretation. − However, molecules with ionization energy (IE) higher than photon energy cannot be ionized. Therefore, SPI is seldom used for detecting inorganic compounds because their IEs are usually higher than 11 eV.…”

Section: Concept and Instrumentation Of The Mepei Sourcementioning

confidence: 99%

“…Photoelectrons generated through photoelectric effect can avoid some disadvantages caused by the hot filament, especially for the working pressure limitation. ,− Zenobi and co-workers discussed the mass spectra with EI characteristics using photoelectrons generated by a VUV lamp in an ion trap mass spectrometer . Our previous work reported a photoelectron ionization (PEI) source which can generate spectra with characteristics of EI under pressure of 0.2 Pa, but the sensitivity for high IE compounds was relatively poor (20 ppmv for SO 2 ) due to the low density of photoelectron emitted (20–30 nA) …”

Section: Concept and Instrumentation Of The Mepei Sourcementioning

confidence: 99%

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Vacuum Ultraviolet Lamp Based Magnetic Field Enhanced Photoelectron Ionization and Single Photon Ionization Source for Online Time-of-Flight Mass Spectrometry

Lee

Hou

et al. 2011

Anal. Chem.

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ABSTRACT:A magnetic field enhanced photoelectron ionization (MEPEI) source combined with single photon ionization (SPI) was developed for an orthogonal acceleration time-of-flight mass spectrometer (oaTOFMS). A commercial radio frequency (rf) powered vacuum ultraviolet (VUV) lamp was used as SPI light source, and the photoelectrons generated by photoelectric effect were accelerated to induce electron ionization (EI). The MEPEI was obtained by applying a magnetic field of about 800 G with a permanent annular magnet. Compared to a nonmagnetic field photoelectron ionization source, the signal intensities for SO 2 , SF 6 , O 2 , and N 2 in MEPEI were improved more than 2 orders with the photoelectron energy around 20 eV, while most of the characteristics of soft ionization still remained. Simulation with SIMION showed that the sensitivity enhancement in MEPEI was ascribed to the increase of the electron moving path and the improvement of the electrons transmission. The limits of detection for SO 2 and benzene were 750 and 80 ppbv within a detection time of 4 s, respectively. The advantages of the source, including broad range of ionizable compounds, reduced fragments, and good sensitivity with low energy MEPEI, were demonstrated by monitoring pyrolysis products of polyvinyl chloride (PVC) and the intermediate products in discharging of the SF 6 gas inpurity.S ingle photon ionization (SPI) is one of the most popular ionization methods used for online monitoring, due to its high molecular ion yield and simple spectrum interpretation. 1À7 However, molecules with ionization energy (IE) higher than photon energy cannot be ionized. Therefore, SPI is seldom used for detecting inorganic compounds because their IEs are usually higher than 11 eV.There are two available methods to expand the range of analytes for SPI. One is using light sources with higher photon energy, such as VUV synchrotron radiation (as high as 13 eV) 8À11 and tunable VUV laser (as high as 11.5 eV limited by window materials). 12 However, the fixed location and expensive cost of the VUV synchrotron radiation obviously limit its applications to mass spectrometry. The disadvantages for tunable VUV laser are the complication and high cost of laser components. The other method to expand the ionization ability is combining a hard ionization source with soft SPI. Zimmermann and co-workers reported a SPI source coupling with a typical hot-filament EI source to ionize compounds through either SPI or EI. 13 However, in most EI sources, the pressure around the filament was kept as low as possible to prolong the lifetime of the heated filament, which limited the molecular density in the ion source and consequently restricted further improvement of the sensitivity. Moreover, hot filament was readily damaged by oxidative gas; thus, it was difficult to analyze air samples directly. Furthermore, fragments and overlapped peaks in standard 70 eV EI

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Section: Application On Monitoring Products In Pyrolysis Of Pvcmentioning

confidence: 99%

Section: Application On Monitoring Products In Pyrolysis Of Pvcmentioning

confidence: 99%

Section: Concept and Instrumentation Of The Mepei Sourcementioning

confidence: 99%

Section: Concept and Instrumentation Of The Mepei Sourcementioning

confidence: 99%

See 2 more Smart Citations

Vacuum Ultraviolet Lamp Based Magnetic Field Enhanced Photoelectron Ionization and Single Photon Ionization Source for Online Time-of-Flight Mass Spectrometry

Lee

Hou

et al. 2011

Anal. Chem.

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“…For a better control of electron production and acceleration as well as the ionization and ion extraction, it is desirable to spatially and temporally separate the two processes. In 1998, Wang et al 20 reported a design of a photoemission electron impact ionizer where the acceleration of electrons and ions are separately controlled. The formation of high Rydberg states of argon and acetylene was demonstrated using the ionizer.…”

Section: Introductionmentioning

confidence: 99%

Development of a new laser induced electron impact ionization source for studying the hot-wire chemical vapor deposition chemistry of silane–ammonia mixtures

Eustergerling

Hedén

Shi

2008

J. Anal. At. Spectrom.

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A newly-developed laser induced electron impact ionization (LIEI) method is presented. In this method, electrons are generated by thermionic emission when directing a low-power, pulsed UV laser beam to a stainless steel rod exterior to the ion optics of a time-of-flight mass spectrometer. The electrons are collimated into a beam almost parallel to the ion optics by the electric field between the rod and a copper mesh placed in the vicinity and the utilization of a delayed ion extraction pulse. It has been demonstrated that EI-type mass spectra can be obtained with a mass resolution that is comparable to that using laser ionization. The detection sensitivity is very high, with a detection limit of < 32 attomole for NH 3 . The gas-phase chemistry of SiH 4 /NH 3 mixtures in the hot-wire chemical vapor deposition (HWCVD) process was examined using the new LIEI source. It is found that this method is well suited for detecting stable species with high ionization potentials, such as H 2 and N 2 , which characterizes the NH 3 decomposition chemistry in a HWCVD reactor. The suppression of NH 3 chemistry by the presence of SiH 4 in the mixture is demonstrated, as is the temperature dependence of the suppression extent.

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A combined single photon ionization and photoelectron ionization source for orthogonal acceleration time-of-flight mass spectrometer

Lee

Hou

et al. 2010

International Journal of Mass Spectrometry

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Application of laser induced photoemission electron in time-of-flight mass spectrometry

Cited by 7 publications

References 18 publications

Vacuum Ultraviolet Lamp Based Magnetic Field Enhanced Photoelectron Ionization and Single Photon Ionization Source for Online Time-of-Flight Mass Spectrometry

Vacuum Ultraviolet Lamp Based Magnetic Field Enhanced Photoelectron Ionization and Single Photon Ionization Source for Online Time-of-Flight Mass Spectrometry

Development of a new laser induced electron impact ionization source for studying the hot-wire chemical vapor deposition chemistry of silane–ammonia mixtures

A combined single photon ionization and photoelectron ionization source for orthogonal acceleration time-of-flight mass spectrometer

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