Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, USA.
J Am Soc Mass Spectrom. 2011 Feb;22(2):207-13. doi: 10.1007/s13361-010-0039-y. Epub 2011 Jan 15.
Infrared multiphoton photodissociation (IRMPD) in a quadrupole ion trap is not selective for a parent ion. Product ions are decreased in abundance by continuous sequential dissociation and may be lost below the low mass cut-off. The IRMPD process is made selective by resonantly exciting trapped ions into an axially offset laser path. Product ions form and collisionally relax out of the laser path to accumulate in the center of the trap. The technique, termed selective broadband (SB) IRMPD, limits sequential dissociation to preserve first generation product ion abundance. The abundances of larger product ions are maximized by completely dissociating the parent ion, but continuous sequential dissociation does not form small product ions below the low mass cut-off associated with conventional IRMPD. Smaller product ions are further increased in abundance in another tandem mass spectrum by performing sequential stages of SB-IRMPD, adjusting the trapping rf amplitude to dissociate larger product ions at the same q(z) range. Thermal assistance is used to perform SB-IRMPD at higher bath gas pressures for increased sensitivity.
四极离子阱中的红外多光子光解（IRMPD）对母离子没有选择性。连续顺序解离会降低产物离子的丰度，并且可能在低质量截止以下丢失。通过将捕获的离子共振激发到轴向偏移的激光路径中，IRMPD 过程变得具有选择性。产物离子形成并从激光路径中碰撞弛豫出来，在阱的中心累积。该技术称为选择性宽带（SB）IRMPD，通过限制顺序解离来保留第一代产物离子的丰度。通过完全解离母离子，可以最大化较大产物离子的丰度，但连续顺序解离不会在与传统 IRMPD 相关的低质量截止以下形成小产物离子。通过执行 SB-IRMPD 的顺序阶段，在另一个串联质谱中进一步增加较小产物离子的丰度，调整捕获 rf 幅度以在相同的 q(z)范围内解离较大的产物离子。使用热辅助在更高的浴气压下进行 SB-IRMPD，以提高灵敏度。
