Suppression of fragmentation in multiphoton ionization mass spectrometry using a near-infrared femtosecond laser as an ionization source,Analyst

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Suppression of fragmentation in multiphoton ionization mass spectrometry using a near-infrared femtosecond laser as an ionization source
Analyst ( IF 3.6 ) Pub Date : 2017-09-14 00:00:00 , DOI: 10.1039/c7an01172e
Adan Li _{1,

2,

3,

4} , Thang Phan Dinh _{5,

6,

7,

8,

9} , Tomoko Imasaka _{7,

9,

10,

11,

12} , Totaro Imasaka _{5,

6,

7,

8,

9}

Affiliation

The ionization and fragmentation processes for pentachlorobenzene were examined using a femtosecond laser emitting at 400, 800, and 1200 nm. A molecular ion was clearly observed in the mass spectrum, since the molecule can be directly ionized from the singlet electronic exited state before relaxation to triplet levels, because the pulse width of the laser is shorter than the lifetime of the excited state. Fragmentation was minimal at 1200 nm, in contrast to ionization at 800 and 400 nm. Indeed, a doubly-charged molecular ion was prominent at 800 nm, owing to the absorption band of the singly-charged molecular ion at this wavelength. Fragmentation was further enhanced at 400 nm, which can be explained by the dissociation of the doubly-charged molecular ion having a larger absorption band at 400 nm. Fragmentation was strongly affected by the absorption character of the ionic species, i.e., singly- and doubly-charged molecular ions, appeared in the process of multiphoton ionization.

中文翻译：

使用近红外飞秒激光作为电离源的多光子电离质谱中的碎裂抑制

使用在400、800和1200 nm发射的飞秒激光检查了五氯苯的电离和裂解过程。在质谱图中可以清楚地观察到分子离子，因为该分子可以在弛豫之前从单重态电子出射态直接电离到三重态，这是因为激光的脉冲宽度比激发态的寿命短。与在800和400 nm处的电离相反，在1200 nm处的碎裂最小。实际上，由于在该波长下单电荷分子离子的吸收带，所以双电荷分子离子在800 nm处很明显。在400 nm处的碎裂进一步增强，这可以通过在400 nm处具有较大吸收带的双电荷分子离子解离来解释。即，单电荷和双电荷分子离子出现在多光子电离过程中。

更新日期：2017-09-21

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