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Duration of an intense laser pulse can determine the breakage of multiple chemical bonds.

Xie X, Lötstedt E, Roither S, Schöffler M, Kartashov D, Midorikawa K, Baltuška A, Yamanouchi K, Kitzler M - Sci Rep (2015)

Bottom Line: Control over the breakage of a certain chemical bond in a molecule by an ultrashort laser pulse has been considered for decades.With the availability of intense non-resonant laser fields it became possible to pre-determine femtosecond to picosecond molecular bond breakage dynamics by controlled distortions of the electronic molecular system on sub-femtosecond time scales using field-sensitive processes such as strong-field ionization or excitation.Supported by quantum chemical simulations we explain our experimental results by the interplay between the dynamics of electron removal and nuclear motion.

View Article: PubMed Central - PubMed

Affiliation: Photonics Institute, Vienna University of Technology, Gusshausstrasse 27, A-1040 Vienna, Austria, EU.

ABSTRACT
Control over the breakage of a certain chemical bond in a molecule by an ultrashort laser pulse has been considered for decades. With the availability of intense non-resonant laser fields it became possible to pre-determine femtosecond to picosecond molecular bond breakage dynamics by controlled distortions of the electronic molecular system on sub-femtosecond time scales using field-sensitive processes such as strong-field ionization or excitation. So far, all successful demonstrations in this area considered only fragmentation reactions, where only one bond is broken and the molecule is split into merely two moieties. Here, using ethylene (C2H4) as an example, we experimentally investigate whether complex fragmentation reactions that involve the breakage of more than one chemical bond can be influenced by parameters of an ultrashort intense laser pulse. We show that the dynamics of removing three electrons by strong-field ionization determines the ratio of fragmentation of the molecular trication into two respectively three moieties. We observe a relative increase of two-body fragmentations with the laser pulse duration by almost an order of magnitude. Supported by quantum chemical simulations we explain our experimental results by the interplay between the dynamics of electron removal and nuclear motion.

No MeSH data available.


Related in: MedlinePlus

(a) Potential energy surfaces (PESs) in the ethylene dication (lower) and trication (upper) calculated by GAMESS as described in the text for the stretch motion of two C-H bonds marked by r1 and r2 in (b). (b) Schematics of the geometry used for the calculation of the PESs shown in (a). See text for details. (c,d) Simulated probability for fragmentation of  into two (c) and three (d) moieties along the reactions (1) and (7), respectively, as a function of delay between the second and third ionization step.
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f4: (a) Potential energy surfaces (PESs) in the ethylene dication (lower) and trication (upper) calculated by GAMESS as described in the text for the stretch motion of two C-H bonds marked by r1 and r2 in (b). (b) Schematics of the geometry used for the calculation of the PESs shown in (a). See text for details. (c,d) Simulated probability for fragmentation of into two (c) and three (d) moieties along the reactions (1) and (7), respectively, as a function of delay between the second and third ionization step.

Mentions: To verify the described scenario that follows from the experimental findings we performed simulations for the three-body fragmentation channel (4) using the quantum chemistry simulation package GAMESS26. We calculated the ground and several excited PES of the doubly and triply charged molecular ion for a stretch motion in the molecular plane of two opposing C-H bonds, see Fig. 4(b) for a schematics. The C-C bond length RCC was fixed to RCC = 2.49 a.u. the H—C—H angle θHCH was fixed to θHCH = 117°, and two C-H internuclear distances were set to RCH = 2.03 a.u. These values correspond to the molecular geometry of neutral C2H4, as obtained from a geometry optimization performed with GAMESS at the Hartree-Fock (HF) level. For the calculation of the PESs, we used the 6-311G** basis set and the complete-active-space method, with two frozen core orbitals, and 10 active HF orbitals.


Duration of an intense laser pulse can determine the breakage of multiple chemical bonds.

Xie X, Lötstedt E, Roither S, Schöffler M, Kartashov D, Midorikawa K, Baltuška A, Yamanouchi K, Kitzler M - Sci Rep (2015)

(a) Potential energy surfaces (PESs) in the ethylene dication (lower) and trication (upper) calculated by GAMESS as described in the text for the stretch motion of two C-H bonds marked by r1 and r2 in (b). (b) Schematics of the geometry used for the calculation of the PESs shown in (a). See text for details. (c,d) Simulated probability for fragmentation of  into two (c) and three (d) moieties along the reactions (1) and (7), respectively, as a function of delay between the second and third ionization step.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4536518&req=5

f4: (a) Potential energy surfaces (PESs) in the ethylene dication (lower) and trication (upper) calculated by GAMESS as described in the text for the stretch motion of two C-H bonds marked by r1 and r2 in (b). (b) Schematics of the geometry used for the calculation of the PESs shown in (a). See text for details. (c,d) Simulated probability for fragmentation of into two (c) and three (d) moieties along the reactions (1) and (7), respectively, as a function of delay between the second and third ionization step.
Mentions: To verify the described scenario that follows from the experimental findings we performed simulations for the three-body fragmentation channel (4) using the quantum chemistry simulation package GAMESS26. We calculated the ground and several excited PES of the doubly and triply charged molecular ion for a stretch motion in the molecular plane of two opposing C-H bonds, see Fig. 4(b) for a schematics. The C-C bond length RCC was fixed to RCC = 2.49 a.u. the H—C—H angle θHCH was fixed to θHCH = 117°, and two C-H internuclear distances were set to RCH = 2.03 a.u. These values correspond to the molecular geometry of neutral C2H4, as obtained from a geometry optimization performed with GAMESS at the Hartree-Fock (HF) level. For the calculation of the PESs, we used the 6-311G** basis set and the complete-active-space method, with two frozen core orbitals, and 10 active HF orbitals.

Bottom Line: Control over the breakage of a certain chemical bond in a molecule by an ultrashort laser pulse has been considered for decades.With the availability of intense non-resonant laser fields it became possible to pre-determine femtosecond to picosecond molecular bond breakage dynamics by controlled distortions of the electronic molecular system on sub-femtosecond time scales using field-sensitive processes such as strong-field ionization or excitation.Supported by quantum chemical simulations we explain our experimental results by the interplay between the dynamics of electron removal and nuclear motion.

View Article: PubMed Central - PubMed

Affiliation: Photonics Institute, Vienna University of Technology, Gusshausstrasse 27, A-1040 Vienna, Austria, EU.

ABSTRACT
Control over the breakage of a certain chemical bond in a molecule by an ultrashort laser pulse has been considered for decades. With the availability of intense non-resonant laser fields it became possible to pre-determine femtosecond to picosecond molecular bond breakage dynamics by controlled distortions of the electronic molecular system on sub-femtosecond time scales using field-sensitive processes such as strong-field ionization or excitation. So far, all successful demonstrations in this area considered only fragmentation reactions, where only one bond is broken and the molecule is split into merely two moieties. Here, using ethylene (C2H4) as an example, we experimentally investigate whether complex fragmentation reactions that involve the breakage of more than one chemical bond can be influenced by parameters of an ultrashort intense laser pulse. We show that the dynamics of removing three electrons by strong-field ionization determines the ratio of fragmentation of the molecular trication into two respectively three moieties. We observe a relative increase of two-body fragmentations with the laser pulse duration by almost an order of magnitude. Supported by quantum chemical simulations we explain our experimental results by the interplay between the dynamics of electron removal and nuclear motion.

No MeSH data available.


Related in: MedlinePlus