Franco Vecchiocattivi(University of Perugia)

Double photoionization ofmolecules by synchrotronradiation

AB + hAB + hνν →→ ABAB2+2+ + 2 e + 2 e--

AA++ + B + B++

RR

AA++ + B + B++

A + BA + B2+2+

Coulombic repulsion:

Vrep(R) =

14.4

R(Å)eV____

effusive molecularbeam source

crossing withsynchrotronUV beam

electron MCPdetector

ionoptics

ion t.o.f.tube

ion positionsensitive detector

effusive molecularbeam source

crossing withsynchrotronUV beam

electron MCPdetector

ionoptics

ion t.o.f.tube

ion positionsensitive detector

ABC + hABC + hνν →→ [ABC] [ABC]2+2+ + 2 e + 2 e--

ABCABC2+2+

AB + CAB + C2+2+

AA++ + BC + BC++

AA++ CC2+2+BCBC++

ABCABC2+2+

tof

BCBC++

ABCABC2+2+

CC2+2+

AA++

NN22O + hO + hνν →→ [N [N22O]O]2+2+ + 2 e + 2 e--

NO+

N2+

N+

O+

(N(N22OO2+2+)*)*→→ NO NO++ + O + O++

NONO++ + N + N++

NN22++ + O + O++

M. Alagia, P. Candori, S. Falcinelli, M. Lavollée,M. Alagia, P. Candori, S. Falcinelli, M. Lavollée,F. Pirani, R. Richter, S. Stranges, F. VecchiocattiviF. Pirani, R. Richter, S. Stranges, F. VecchiocattiviChem. Phys. Lett. 432, 398 (2006).Chem. Phys. Lett. 432, 398 (2006).

NN22O + hO + hνν →→ [N [N22O]O]2+2+ + 2 e + 2 e--

(N(N22OO2+2+)*)*→→ NO NO++ + N + N++

NONO++ + N + N++

NN22++ + O + O++

N+

O+

(N(N22OO2+2+)*)*→→ NO NO++ + O + O++

NONO++ + N + N++

NN22++ + O + O++

M. Alagia, P. Candori, S. Falcinelli, M. Lavollée,M. Alagia, P. Candori, S. Falcinelli, M. Lavollée,F. Pirani, R. Richter, S. Stranges, F. VecchiocattiviF. Pirani, R. Richter, S. Stranges, F. VecchiocattiviChem. Phys. Lett. 432, 398 (2006).Chem. Phys. Lett. 432, 398 (2006).

N2O + hν → N+ + NO+

N2O + hν → N2+ + O+

vertical threshold vertical threshold for double for double photoionizationphotoionization

Threshold forThreshold for(N(N22OO2+2+)*)*→→ NO NO++ + O + O++

effusive molecularbeam source

crossing withsynchrotronUV beam

electron MCPdetector

ionoptics

ion t.o.f.tube

ion positionsensitive detector

UV light polarization directionUV light polarization direction

ABC + hABC + hνν →→ A A++ + BC + BC++ + 2 e + 2 e--

AA++BCBC++

O+N2+

NO+ N+

NN22O + hO + hνν →→ N N++ + NO + NO++ + 2e + 2e--

39 eV39 eV

NN22O + hO + hνν →→ N N22++ + O + O++ + 2e- + 2e-

39 eV39 eV

M. Alagia, P. Candori, S. Falcinelli, M. Lavollée, F. Pirani, R. Richter, S. Stranges, F. Vecchiocattivi,M. Alagia, P. Candori, S. Falcinelli, M. Lavollée, F. Pirani, R. Richter, S. Stranges, F. Vecchiocattivi,J. Chem. Phys. 126, 201101 (2007)J. Chem. Phys. 126, 201101 (2007)..

M. Alagia, P. Candori, S. Falcinelli, M. Lavollèe, F. Pirani, R. Richter, S. Stranges, F. Vecchiocattivi,J. Phys. Chem. A 113, 14755, (2009)

M. Alagia, P. Candori, S. Falcinelli, M. Lavollée, F. Pirani, R. Richter, S. Stranges and F. Vecchiocattivi,Phys. Chem. Chem. Phys. 12, 5389 (2010).

Double photoionization of benzene

threshold energy

24.65 ± 0.03 eV

27.8 ± 0.1 eV

29.5 ± 0.1 eV

30.2 ± 0.1 eV

C6H6 + hν → C6H62+ + 2 e-

→ C5H3+ + CH3

+

→ C4H3+ + C2H3

+

→ C4H4+ + C2H2

+

→ C3H3+ + C3H3

+ ?

C6H6 + hν → C6H62+ + 2 e-

→ C5H3+ + CH3

+

→ C4H3+ + C2H3

+

→ C4H4+ + C2H2

+

CH2=C=C=CH2+ + CHCH+

C=C=CH2 + CH3+

HC |HC

+

+ CH2CH+HC—C | | HC—CH

+

B. BrunettiB. BrunettiP. CandoriP. CandoriS. FalcinelliS. FalcinelliM. S. Pedrosa MundimF. PiraniF. PiraniM. RosiM. Rosi

UniversitUniversitàà di Perugia di Perugia

M. AlagiaM. AlagiaR. RichterR. Richter

Sincrotrone TriesteSincrotrone Trieste

S. StrangesS. Stranges

UniversitUniversitàà di Roma di Roma““La SapienzaLa Sapienza””

UniversitUniversitéé Paris-Sud Paris-Sud

M. LavollM. Lavollééee