High resolution tandem mass spectrometry has been applied to obtain the structure information of petroleum samples. Here, we report a method for structural characterization of crude oil molecules by the collision-indu...High resolution tandem mass spectrometry has been applied to obtain the structure information of petroleum samples. Here, we report a method for structural characterization of crude oil molecules by the collision-induced dissociation(CID) technology coupled with the high-field Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS). The ion isolation window was narrowed down to 1 Da to distinguish the complex homologues contained in petroleum. Aromatic model compounds and crude oil samples were measured by CID FT-ICR MS at different collision energy levels. The fragmentation of model compounds with alkyl side-chains was found to be related to the size of the aromatic rings. The fragmentation of model compounds with archipelago structures depended on the length of the bridge alkylene chain. The prevalent reaction pathway of model compounds with naphthenic rings was mainly determined by the position of naphthenic rings in the molecules. On the basis of the fragmentation pathways, the structure differences of two crude oils were recognized as different content of naphthenic rings by CID technology with 1 Da isolation window. The NMR analysis was also applied to confirm the CID results. This study exhibits the great potential of CID FT-ICR MS with narrow isolation window in the structural characterization of crude oil molecules.展开更多
In this study,we present a physical model to explain the generation mechanism of nonlinear periodic waveswith a large amplitude electric field structures propagating obliquely and exactly parallel to the magnetic fiel...In this study,we present a physical model to explain the generation mechanism of nonlinear periodic waveswith a large amplitude electric field structures propagating obliquely and exactly parallel to the magnetic field.The'Sagdeev potential' from the MHD equations is derived and the nonlinear electric field waveforms are obtained when theMach number,direction of propagation,and the initial electric field satisfy certain plasma conditions.For the parallelpropagation,the amplitude of the electric field waves with ion-acoustic mode increases with the increase of initial electricfield and Mach number but its frequency decreases with the increase of Mach number.The amplitude and frequency ofthe electric field waves with ion-cyclotron mode decrease with the increase of Mach number and become less spiky,andits amplitude increases with the increase of initial electric field.For the oblique propagation,only periodic electric fieldwave with an ion-cyclotron mode obtained,its amplitude and frequency increase with the increase of Mach number andbecome spiky.From our model the electric field structures show periodic,spiky,and saw-tooth behaviours correspondingto different plasma conditions.展开更多
LECR2 (Lanzhou ECR ion source No. 2) has been used to provide multiply charged ion beams for HIRFL cyclotron for many years. This source works at 14.5 GHz and is designed according to the high-B mode theory. Optimum d...LECR2 (Lanzhou ECR ion source No. 2) has been used to provide multiply charged ion beams for HIRFL cyclotron for many years. This source works at 14.5 GHz and is designed according to the high-B mode theory. Optimum design, good enough vacuum condition and the other favored conditions make this source be performed reliably and highly. Till now, the controlling of the source is still working under the long-distance manual analog controlling status.展开更多
基金supported by the Key Laboratory of SINOPEC (KL17010)the research project of Research Institute of Petroleum Processing(R16075)
文摘High resolution tandem mass spectrometry has been applied to obtain the structure information of petroleum samples. Here, we report a method for structural characterization of crude oil molecules by the collision-induced dissociation(CID) technology coupled with the high-field Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS). The ion isolation window was narrowed down to 1 Da to distinguish the complex homologues contained in petroleum. Aromatic model compounds and crude oil samples were measured by CID FT-ICR MS at different collision energy levels. The fragmentation of model compounds with alkyl side-chains was found to be related to the size of the aromatic rings. The fragmentation of model compounds with archipelago structures depended on the length of the bridge alkylene chain. The prevalent reaction pathway of model compounds with naphthenic rings was mainly determined by the position of naphthenic rings in the molecules. On the basis of the fragmentation pathways, the structure differences of two crude oils were recognized as different content of naphthenic rings by CID technology with 1 Da isolation window. The NMR analysis was also applied to confirm the CID results. This study exhibits the great potential of CID FT-ICR MS with narrow isolation window in the structural characterization of crude oil molecules.
基金Supported by National Natural Science Foundation of China under Grant Nos.40674091 and 40621003the Specialized Research Fund for State Key Laboratories
文摘In this study,we present a physical model to explain the generation mechanism of nonlinear periodic waveswith a large amplitude electric field structures propagating obliquely and exactly parallel to the magnetic field.The'Sagdeev potential' from the MHD equations is derived and the nonlinear electric field waveforms are obtained when theMach number,direction of propagation,and the initial electric field satisfy certain plasma conditions.For the parallelpropagation,the amplitude of the electric field waves with ion-acoustic mode increases with the increase of initial electricfield and Mach number but its frequency decreases with the increase of Mach number.The amplitude and frequency ofthe electric field waves with ion-cyclotron mode decrease with the increase of Mach number and become less spiky,andits amplitude increases with the increase of initial electric field.For the oblique propagation,only periodic electric fieldwave with an ion-cyclotron mode obtained,its amplitude and frequency increase with the increase of Mach number andbecome spiky.From our model the electric field structures show periodic,spiky,and saw-tooth behaviours correspondingto different plasma conditions.
文摘LECR2 (Lanzhou ECR ion source No. 2) has been used to provide multiply charged ion beams for HIRFL cyclotron for many years. This source works at 14.5 GHz and is designed according to the high-B mode theory. Optimum design, good enough vacuum condition and the other favored conditions make this source be performed reliably and highly. Till now, the controlling of the source is still working under the long-distance manual analog controlling status.
