Secondary electron emission in proton-Uracil collision: preliminary

resultsP.Moretto-Capelle D.Bordenave-Montesquieu A.Bordenave-Montesquieu(A.Rentenier)

Future members:A.LepadellecM.Richard-Viard

IRSAMC, LCAR, UMR 5589 CNRS-Univ.P.Sabatier118 rte de Narbonne, 31062 TOULOUSE CEDEX, FRANCE

Study of the damages created on bio molecules by

ion impactInteraction of ions with matter: possibility of strong energy deposition in a well defined region around the Bragg peak

Treatment of Tumour: Proton/Hadron therapy

Energetic ion

e-

Link between ion interaction and DNA damages?

Fragmentation, ionization of

bases

Radiolysis of Water H, HO

Secondary electron emission

Effects of secondary electrons…

Dissociatif attachment

Huo et al Radiation2004

Tracks:

E<20

eV

E>20eV

Initial electron spectrum??

Boudaiffa, ScienceFrom GSI

Ionization

Our interest…Electrons!

H+ (H0) in the 100keV energy range (Bragg peak)

Spectroscopy and angular distribution (doubly differential cross sections) of secondary electrons emitted after ion-biomolecule interaction

Biomolecule in gaz phase:H2O, Bases of RNA, DNA: Uracil, Cytosine, Thymine…

Electron spectroscopy correlated with fragmentation

Future: Solvated biomolecule (coll M.and B. Farizon)

Biomolecule on surface (M.Richard-Viard)

Experimental apparatus

Cylindrical electron analyser

‘Total’ electron detector

Oven

IonTime of flight

spectrometer

Ion beam 1-150keV*Continuous*Pulsed 5ns

High resolution electron

spectrometer

OVEN 120°

Uracil JET

Cylindrical Mirror Analyser e- Spectroscopy

Time of flight cell Ions, fragments

Ion beam Beam pulser (dT5ns)

STOP(S)

Multi-Stop

7885 FAST 5ns resol

START

Mixing, Delay

600V/cm Pulsed extraction (1800V in 10ns)

First experimental results: H++Uracil

Test of the Jet: Fragmentation

20 40 60 80 100 120 1400

1000

2000

3000

4000

Mass over charge

100 keV

0

500

1000

1500

2000

2500

Num

ber o

f cou

nts

50 keV

200

400

600

800

1000

1200

25 keV

0 10 20 30 40 50 60 70 80 90 100110120130140

500

1000

1500

2000

2500

Nu

mb

er

of

co

un

ts

Mass over charge

C,CH,N

,NH,O

H+ + Uracil 50 keV

20 40 60 80 100 120 140 160 180 2000

200

400

600

Deposited energy (eV)

20 40 60 80 100 120 140 160 180 2000

200

400

600

dN/dE

dep

20 40 60 80 100 120 140 160 180 2000

200

400

600

Energy deposited in Uracil(calculation)

Electron spectroscopy: H+(100keV) + Uracil

10 1001E-5

1E-4

1E-3

0.01

Inte

nsi

ty (

arb

.un

it)

Electron energy (eV)

e-H+

35°

Denifl et al

Chem.Phys.Lett 2003

H2O

C

T

U

Electron

Collision energy dependence

50 100 150 200 250 3001E-6

1E-5

1E-4

1E-3

0.01

Inte

nsity

(ar

b. u

nit)

Electron energy (eV)

25keV50keV100keV

20 30 40 50 60 70 80 90 100 110

1.0

1.5

2.0

2.5

3.0

3.5

Inte

nsi

tyIn

ten

sity

(25k

eV)

Collision energy (keV)

Increase of <electron energy> with collision

energy

Corresponding intensity

Link between electron emission and fragmentation?

Not yet investigated in ion / bio molecule collision… But in H3

+ + C60 collision

0.1

1

10

Inte

nsity

Total electron spectrum

7 6 5 4 3 2 1 0

Intensity

Cn

+ (n=2-15)

C60

+

C60

2+

C60

3+

20 40 60 80 100 120 140 160 180

600

800

1000

1200

1400

1600

1800

Tim

e of

flig

ht

Electron energy (eV)

20 40 60 80 100 1200.01

0.1

1

Electron energy (eV)

Multifrag (/20)

C+

60

Partial spectra

Electron spectrum depends of fragmentation pattern

Average energy of the electrons:

Stable ions Evap/fission Multifragmentation

<Ec>=19 eV 24 eV 28 eV

Interpretation

02

46

810

0

50

100

150

200

0 40 80 120 160 200

1E-8

1E-6

1E-4

0.01

1

Electron energy (eV)

Impac

t par

amete

r (ua)

Deposited energy (eV)

Intensity (arb.unit)

Small impact parameter: high energy electron AND high energy deposited Large impact parameter: low energy electron AND low energy deposited

Key parameter: impact parameter Biomolecules???

Summary

For questions about this presentation, please write to

Patrick Moretto-Capelle

pmc@irsamc.ups-tlse.fr

Spectroscopy of electrons emitted after H++ biomolecules (DNA, RNA bases) in gas phase

Correlation between electron spectroscopy and fragmentation

I (PMC) would like to thank sincerely M.Richard-Viard for the presentation of this talk at the conference.