一、一般介绍质谱法是常用的测定分子量及分子结构的方法,但对于非挥发性的或者是对热不稳定的生物大分子,很难获得它们的质谱。1974年Macfarlane和他的同事首先应用次级离子质谱（Secondary Ion Mass Spectrometry SIMS）介决这一难题...一、一般介绍质谱法是常用的测定分子量及分子结构的方法,但对于非挥发性的或者是对热不稳定的生物大分子,很难获得它们的质谱。1974年Macfarlane和他的同事首先应用次级离子质谱（Secondary Ion Mass Spectrometry SIMS）介决这一难题。其初级粒子可用放射性同位素252Cf的裂变碎片或经加速器加速的高能重粒子或短脉冲的激光束,将不易气化的生物大分子溅射出,形成准分子离子。后用时间飞行谱仪测其质量。展开更多
A serious problem in secondary ion mass spectrometry (SI MS ) analysis is its “matrix effect” that hinders the quantification of a certain species in a sample and consequently, appropriate corrective measures are ta...A serious problem in secondary ion mass spectrometry (SI MS ) analysis is its “matrix effect” that hinders the quantification of a certain species in a sample and consequently, appropriate corrective measures are taken to calibrate the secondary ion currents into respective concentrations for accu rate compositional analysis. Use of “calibration standards” is necessary for t his purpose. Detection of molecular MCs_n+ ions (M-element to be analyz ed , n=1, 2, 3,….) under Cs+ ion bombardment is a possible mean to minimiz e such matrix effect, enabling one to quantify without the need of calibration sta ndards. Our recent studies on MCs_n+ molecular ions aim towards the understanding of their formation mechanisms, which are important to know their e ffects on SIMS quantification. In-depth quantitative analysis is a major strength of SIMS for which ‘depth resolution’ is of significant relevance. The optimal choice of the impact pa rameters during SIMS analyses can play an effective role in obtaining data with ultra-high depth resolution. SIMS is possible at depth resolution in the nm or even sub-nm rang e, with quantifiable data obtained from the top monolayer onwards into the material. Wi th optimized experimental conditions, like extremely low beam current (down to ～10 nA), and low bombarding energy (below 1 keV), ultra-high depth resolution SIMS has e nabled interfacial composition analysis of ultra-thin films, quantum wells, heterostru ctures, etc. and complex low-dimensional structures with high precision and re peatability.展开更多
文摘一、一般介绍质谱法是常用的测定分子量及分子结构的方法,但对于非挥发性的或者是对热不稳定的生物大分子,很难获得它们的质谱。1974年Macfarlane和他的同事首先应用次级离子质谱（Secondary Ion Mass Spectrometry SIMS）介决这一难题。其初级粒子可用放射性同位素252Cf的裂变碎片或经加速器加速的高能重粒子或短脉冲的激光束,将不易气化的生物大分子溅射出,形成准分子离子。后用时间飞行谱仪测其质量。
文摘A serious problem in secondary ion mass spectrometry (SI MS ) analysis is its “matrix effect” that hinders the quantification of a certain species in a sample and consequently, appropriate corrective measures are taken to calibrate the secondary ion currents into respective concentrations for accu rate compositional analysis. Use of “calibration standards” is necessary for t his purpose. Detection of molecular MCs_n+ ions (M-element to be analyz ed , n=1, 2, 3,….) under Cs+ ion bombardment is a possible mean to minimiz e such matrix effect, enabling one to quantify without the need of calibration sta ndards. Our recent studies on MCs_n+ molecular ions aim towards the understanding of their formation mechanisms, which are important to know their e ffects on SIMS quantification. In-depth quantitative analysis is a major strength of SIMS for which ‘depth resolution’ is of significant relevance. The optimal choice of the impact pa rameters during SIMS analyses can play an effective role in obtaining data with ultra-high depth resolution. SIMS is possible at depth resolution in the nm or even sub-nm rang e, with quantifiable data obtained from the top monolayer onwards into the material. Wi th optimized experimental conditions, like extremely low beam current (down to ～10 nA), and low bombarding energy (below 1 keV), ultra-high depth resolution SIMS has e nabled interfacial composition analysis of ultra-thin films, quantum wells, heterostru ctures, etc. and complex low-dimensional structures with high precision and re peatability.
