This paper studies supersonic jet-cooled 1-fluoronaphthalene （1FN） clusters by ultraviolet （UV） laser ionization at 281 nm in a time-of-flight mass spectrometer. The （1FN）＋ （n=1-3） series cluster ions are obs...This paper studies supersonic jet-cooled 1-fluoronaphthalene （1FN） clusters by ultraviolet （UV） laser ionization at 281 nm in a time-of-flight mass spectrometer. The （1FN）＋ （n=1-3） series cluster ions are observed where the signal intensity decreases with increasing cluster size. The effects of sample inlet pressures and ionization laser fluxes to mass spectral distribution are measured. Using density functional theory calculations, it obtains a planar geometric structure of 1FN dimer which is combined through two hydrogen bonds. The mass spectra indicate that the intensity of 1FN trimer is much weaker than that of 1FN dimer and this feature is attributed to the fact that the dimer may form the first ＂shell＂ in geometric structure while the larger clusters are generated based on this fundamental unit.展开更多
选用肽质量指纹谱(peptide mass fingerprint,PMF)技术鉴定质谱纯海兔肝铁蛋白(liver ferritin ofAplysia,ALF)。来源于基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)仪中的激光和基质芥子酸协同解吸海兔肝铁蛋白(ALF)为带双电荷、...选用肽质量指纹谱(peptide mass fingerprint,PMF)技术鉴定质谱纯海兔肝铁蛋白(liver ferritin ofAplysia,ALF)。来源于基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)仪中的激光和基质芥子酸协同解吸海兔肝铁蛋白(ALF)为带双电荷、单电荷[M+H]+和二聚体的亚基离子,并可供质谱分析。ALF亚基的质荷比m/z分别为9784.03[M+2H]2+、19678.42[M+H]+和39387.80[2M+H]+,其中亚基分子量[M+H]+略小于鲨鱼肝铁蛋白(liver ferritin of shark,SLF)。在弱碱介质(pH8.0)条件下,电子光谱技术研究指出,抗坏血酸以1/2级反应方式参与ALF释放铁全过程,同时又使ALF以一级反应动力学方式释放铁,呈现两种不同的速率。推测这一异常现象可能与ALF含低铁量、亚基调节能力和海兔的进化地位有关。展开更多
文摘This paper studies supersonic jet-cooled 1-fluoronaphthalene （1FN） clusters by ultraviolet （UV） laser ionization at 281 nm in a time-of-flight mass spectrometer. The （1FN）＋ （n=1-3） series cluster ions are observed where the signal intensity decreases with increasing cluster size. The effects of sample inlet pressures and ionization laser fluxes to mass spectral distribution are measured. Using density functional theory calculations, it obtains a planar geometric structure of 1FN dimer which is combined through two hydrogen bonds. The mass spectra indicate that the intensity of 1FN trimer is much weaker than that of 1FN dimer and this feature is attributed to the fact that the dimer may form the first ＂shell＂ in geometric structure while the larger clusters are generated based on this fundamental unit.
文摘选用肽质量指纹谱(peptide mass fingerprint,PMF)技术鉴定质谱纯海兔肝铁蛋白(liver ferritin ofAplysia,ALF)。来源于基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)仪中的激光和基质芥子酸协同解吸海兔肝铁蛋白(ALF)为带双电荷、单电荷[M+H]+和二聚体的亚基离子,并可供质谱分析。ALF亚基的质荷比m/z分别为9784.03[M+2H]2+、19678.42[M+H]+和39387.80[2M+H]+,其中亚基分子量[M+H]+略小于鲨鱼肝铁蛋白(liver ferritin of shark,SLF)。在弱碱介质(pH8.0)条件下,电子光谱技术研究指出,抗坏血酸以1/2级反应方式参与ALF释放铁全过程,同时又使ALF以一级反应动力学方式释放铁,呈现两种不同的速率。推测这一异常现象可能与ALF含低铁量、亚基调节能力和海兔的进化地位有关。
