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éB±Ìè@ÉæèCSASE_FEL XyNgÌÎçÂ«ðj^[µC½õq½dCI»ßöÌõqGlM[Ë¶ÌÚ×ðN¾ÉÅ«é±Æð¦·BÉ[OiEUVjÌæÌ SASE_FEL ÌoêÉæèCéõdqúoÌ½µÉæÁÄ¾éCIÌ^®ÊÌÏª©

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Á½ñüÌ¤ªißçêÄ«½ªC½¿CIÌ¶¬É¢½é½`õwßöÉÎ·éîbIÈ»¡ÉÁ¦C{ÁWÅàõqzûªÇÌæ¤Éis·é©ÉÂ¢ÄÌðÍ¢¾À

zû_Ci~NXÆ¢¤±êÜÅ¤ª¢ïÅÐî³êÄ¢éæ¤Èá·§xvY}¶¬âõXCbèIÅ`OC¶ÌªqC[WOÌ«IÈ FEL pÖ

ÔÜ½ÍIóÔÌdqóÔÍC»ÌßöÅúo³êéõdéBêûCCI»ßöÉ¨¢Ä¶¬·éÔóÌîbIm©ÆµÄC±Ìñü`õw»ÛÌðªdvqÌ^®GlM[É¼ÚIÉ½f³êé±Æ©çCõd³êÄ¢é½ßÅéÇ§qªõÉæè½õq½dCI»ßöÉÂ¢ÄæèÚ×È´qÍCV½Èñü`õwßöð¾ç©É·é¤¦ÅCi

îñð±«o·±ÆªÅ«é5) B±êÉÁ¦ÄCSASEDÌx`}[NÅ[hÌ FEL Ìh½ÅéBÅàVvÈ¨¿nÅéBÀÛCæsµÄ[U[pªéXyNgÌÎçÂ«ðV

nÜÁ½hCcÌ FLASH É¨¢ÄàC»ÌpÌbg²ÆÉj^[·é±ÆªÅ«é½ßCõdqªõÉ©ç»ÝÜÅC´qæÁÄ½õq½dCI»ÌõqGlM[Ë¶«ð¸§é¢ÍÈPÈªqðÎÛÆµ½ñü`õw»ÛÌ¤ª[U[pÌå«ÈðèßÄ¢É²×é±ÆªÂ\ÆÈéBúËõðõ¹Æµ½ªð\õdqªõÀ±ÅÍCÃdéBZg·­[U[êÉ¨¯é´qÌñü`õwÆµÄÅà°ÈßöÍC½õqzûÉæé½dCI»Å¼^ÌõdqªÍíÌpª»ÝÌå¬ÅéBµ©µÈªçCåëªoÍÌ FEL ðõ¹Æ·éõdqªõÀ±éB±ÌßöÌF¯©ÌÍC¶¬µ½CIðo·é±ÅÍCoø¦Ìá¢Ãd¼ÆÉæèärIÈÖÉs¤±ÆªÅ«éBá¦ÎC13.3

pÍK³È¢B±êÍC½Ì×d±qªêxÉ¶¬·^Ìæ¤ÈõdqªÍíÌ

nm Ì FEL Éæé7.8~1015 W/cm2 Ì[U[êÉ¨¢é±ÆÉæéóÔd×øÊðð¯é½ßÉCÉßÄá¢õÄCXe Ì½õq½dCI»Éæè Xe21{ ª¶¬·é±d£Cxg[gÅªè·é±Æªv³êé½ßÅ

Æª©¢¾³êÄ¢é1)B±Ì Xe21{ Ì¶¬ÉÍ57õqªéBäXÍC¥C~[øÊðpµ½´ø¦ÌõdqÌGlM[Ìt^ªKvÅéªC±êªí¯IÈ½õªõè@C¥C{g^dqªÍð FEL À±ÉpµÄqzûÅðÅ«éÌ©Í_¤àÜßÄå«ÈÖSª¢éBFig. 1 ÉäXªp¢Ä¢é¥C{g^õdqªõñ¹çêÄ¢é2)BÜ½CôÂ©Ì½õq½dCI»ÌíÌTO}ð¦·B¥C{g^õdqªÍíÅÍCivP[XÉÂ¢ÄCCIûÊÌ FEL ­xË¶©çzû³¥ÎÆ\mChRCÉæÁÄ`¬µ½¥êùzÉæÁêéõqª©ÏàçêC»Ì½dCI»ÌJjYÄCõd£Åúo³ê½SdqðS§ÌpÉí½ÁÄßWªè³êÄ¢é3)B³çÉC½õq½dCI»É¨¯·éBÀÛC\ eV ÈºÌdqÉÎ·éoø¦ÍC

úËõ Sept. 2010 Vol.23 No.5  291(C) 2010 The Japanese Society for Synchrotron Radiation ResearchFig. 1.

Schematic view of the magnetic bottle electron energy
analyzer which has been adapted for our photoelectron spec­troscopic study with EUV SASE_FEL.
Fig. 3.

(a) Intensity of the Ar{ photoelectron peak and total inten­
sity of the Ar2{ ones (peaks in the kinetic energy range of 10_16 eV) as a function of the FEL power, derived from theshot­by­shot analysis of the photoelectron spectra at an FEL
setting to 21.4 eV photon energy. The curves show the ts
with a set of rate equations formulated for the sequential
three­photon double ionization mediated by Ar{resonances. (b) Energy diagram depicting sequential double
ionization due to three photon absorption.

»Éæé Ar{ ¶¬ÉÎ·és[Ni^®GlM[ª5.5 eV tßjÉÁ¦CO{Ìs[Nª10_16 eV ÉÏª³
êéB±Ì10_16 eV Ì\¢ÍC1 õqCI»ÅÍS­Fig. 2.

Photoelectron spectrum of Ar obtained by 15000 FEL shotsat a photon energy setting to 21.4 eV. The photoelectron ki­
netic energies expected in two­photon ionization of Ar{
3p|1 into Ar2{ 3p|2, as well as those expected in one­pho­
ton ionization of Ar into Ar{ 3p|1, are indicated. In the in­set, the mean photon energies determined from the Ar{
3p|1 peak energies in the individual single­shot spectra areplotted against the intensities of the corresponding FEL
shots which are monitored by a photoion yield detector.

ðßÅ«¸C¾ç©É½õqzûÉNö·éBÀÛÉ10_16 eV Ìs[N\¢Ì­xð FEL pX­xÉÎµÄvbg·éÆiFig. 3(ajjC1 õqCI»Éæé Ar{ ¶¬Ìs[N­xÌË¶«Éä×ÄX«ª}sÅ

èCñü`Èð©ÄÆêéB±êçÌ 3 {Ìs[NÍC»Ì^®GlM[©çCAr{ ©çÌ 2 õqCI»Éæè
Ar2{ îêdqzuÌÙÈé 3 ÂÌÊª¶¬µ½àÌÆA®Å«éB·Èí¿CSßöÅÍ Fig. 3(b)ÌGlM[}É¦µ½æ¤È 3 õqzûÉæéiKIÈ 2 dCIoí}CN`lv[gÌo´xi50_60÷ö

»ßöªN±ÁÄ¢é±ÆÉÈéBAr{ ©ç Ar2{ ÖÌ 2xjÉæÁÄè³êÄ¨èC¥êÉæéßWÌæè±ÚõqCI»É¨¢ÄÍCÔóÔÆÈè¾é Ar{ ÌãµÍ©çêÈ¢B±êÍC»ÝÌWIÈÃd¼NóÔª¶Ý·éB±ÌÔóÔÖÌ¤ÂÌ½ßÉ½dC^dqGlM[ªÍíªS§ÌpÌ0.1÷öxµ©ßWµÄ¢I»ßöÍ FEL ÌõGlM[ÉsqÉË¶·é±ÆÈ¢±Æðl¦éÆC§ÌpÅ 2ªúÒ³êéBµ©µÈªçCSASE [hÌ FEL ÅÍÈãàø¦ªÇ¢B½¾µC¥C{g^õdqªÍÅÍõdqÌòsÔÉVbg²ÆÉ FEL XyNgÉÎçÂ«ªæè^®GlM[ªÍðs¤½ßC¢^®GlM[Éæè¤ÂøÊÍsN¾ÉÈÁÄµÜ¤B

èC±êªð\ð¾é±Æªïµ¢BäXÌuÅÍ1.5 m Ì·¢1 õqCI»Éæéõdqs[NÌvt@CÍòsæÔÆj~dêÉæèªð\Ìüãð}ÁÄ¨èC

FEL XyNgð½f·éB»Ì½ßCõdqs[NÌ\ eV ÈºÌdqÉÎµ÷ÈºÌªð\ðB¬µÄ¢éB

vt@CðVbg²ÆÉÏª·êÎCSASE [h±Ì¥C{g^õdqªÍíðp¢½õdqªõÉæÅÌe FEL XyNgÌÎçÂ«ðj^[·é±ÆªÁÄC»ÝÜÅÉôÂ©ÌT^IÈ½õq½dCI»ßÂ\ÅéBÀÛCFig. 2 ÌªèÌVbg²ÆÌõdq

öðÏªµC»ÌJjYÌÚ×ð¾ç©É·é±ÆÉ

XyNgð²¸·éÆCFEL XyNgÌÎçÂ«ð¬÷µÄ¢éB±±ÅÍCAr Ì 3 õq 2 dCI»Ì½fµÄCAr{ s[NÌ^®GlM[ªeVbgÅP[X6) ÉÂ¢ÄTà·éBFig. 2 ÍCõGlM[21.4Ï»µÄ¢é±Æª©o¹éBFig. 2 Ì}ü}ÍC»ÌVeVC[U[dêñ 5 TW/cm2 ÉæÁÄ¾çê½ Ar Ìbg²ÆÌ Ar{ s[NÌ^®GlM[©ç©ÏàÁõdqXyNgÅ½ FEL XyNgÌSGlM[ðC»Ìe FEL p

éB±ÌXyNgÍC15000VbgÌ FEL pXÉÂ¢ÄÌÏZÅ292  úËõ Sept. 2010 Vol.23 No.5

éB1 õqCIXÌ­xir[CÉõ¦çê½õ­xj^[©

EUV SASE_FEL pÌWJ ¡ EUV SASE_FEL ðp¢½´qÌ½õq½dCI»ßöÌ¤

Fig. 5.

Fig. 4.

Photoelectron spectra in the range of the Ar2{ 3p|2 peaks,
derived from a single­shot­basis analysis. In the analysis, thesingle­shot photoelectron spectra obtained at three dierent
nominal FEL photon energies of 21.0, 21.2 and 21.4 eV
were sorted by the mean photon energies determined fromthe Ar{ 3p|1 peak energies, and then averaged within nar­row photon energy ranges that divide the whole photon
energy range into 13 segments.

Time evolution of state populations of Ar irradiated withFEL pulses of the laser elds of 1~1012 W/cm2 and 1~1013W/cm2, which are derived from the t with rate equations ofthe FEL intensity dependences of the Ar{ and Ar2{ signalintensities plotted in Fig. 3(a).

ö®ÅtBbg·é±ÆªÅ«éB±ÌtBbg©ç¾ç
ê½ FEL pXÌüËÉ¶½ Ar ÌóÔªzÌÏ»ð
Fig. 5 É¦µ½B[U[ê­x 1~1012 W/cm2 É¨¯éAr ÍC»Ì40÷ÈãÍÅIIÉ 2 ¿CIÉB·é±Æª ª© éB ³ç ÉC [ U[ dê ª 1~1013 W /cm2 ÅçÌM­xjÉÎµÄvbgµ½àÌÅéB0.13ÍCÀ¿IÉSÄÌóÔªzÍ2¿CIÆÈéB±ÌæeV Ì¼lSðàÂSGlM[ÌÎçÂ«ªÏª³¤È°È 2 ¿CI¶¬ÍC±ÌõqGlM[ÅÌêéªC±ÌªzÍÊÌõwIè@ÉæéÏªÆÉßÄÇø¦IÈ Ar{ ÌãNóÔÖÌ¤ÂÉæéàÌÅéB­êv·é7)B·Èí¿C±ÌõdqªõÉæéVbg{eÅÍCVOVbgõdqªõÉîÃ­C´q²ÆÌõqGlM[Ìj^[ÍÃÉ@\µÄ¨èCÌ½õq½dCI»ßöÌÚ×È¤ÉÂ¢ÄÐîµ±êðpµÄ FEL XyNgÉsqÉË¶·é½õq

½B»ÝCõw[U[Æ FEL ÆÌ¹pÉæé½õq½½dCI»ßöÌ¤ÂøÊÉAv[`·é±ÆªÂ\dCI»ßöÌæè[¢ðÆ»Ì§äÉü¯½¤ðÆÈÁ½BißÄ¢éBFig. 4 ÍCÂXÌ FEL VbgÌõdqXyNgÉÂ¢ ÄC Ar{ s [N Êu ©ç © Ïà çê ½õ qG lÓ«M[Å\[gµC30 meV ÌõqGlM[ÍÍÉÂ¢Ä{eÅÐîµ½C¥C{g^õdqªÍíðp¢½´Ïª·é±ÆÉæè¾çê½ Ar2{ s[N\¢ÌõqGlqÌ½õq½dCI»ÉÂ¢ÄÌõdqªõÀ±ÍCÉ

éB±Ì0.4 eV ÌõqGlM[Ìæ­p¡y³öC¼cWFmC\Ámiªq¤jÆðJo[·é½ßÉCFEL ÌõqGlM[ÌSlÌ¤ X ü©Rdq[U[væ¯i{pO[vÝèð21.0 eV, 21.2 eV, 21.4 eV ÆµC»êçÅÌªèðÆÌ¤¯¤ÉæéàÌÅ·B

M[Ë¶«ÅÚµÄ¢éBI¶¬·é Ar2{ Ì 3 ÂÌÊÍC¢¸êQl¶£àõqGlM[ª¢¤Å¶¬Êªå·é±Æª©ÄÆêéB±êÍCÔóÔÆÈé Ar{ ÌãNóÔÖÌ¤Âª21.2_21.4 eV tßÉ¶Ý·é±ÆÉÎ·éB±Ì­xÏ»ÌæèÚ×ÈðÍ©çCI¶¬·é Ar2{ ÌÊÉ¶ÄÙÈé Ar{ ÌãNóÔÖÌ¤ÂªÖ^µÄ¢é±Æªª©é6)BÜ½CõqGlM[ÌÁÉº¤^®
GlM[ÌÏ»ÉàC±Ì¤ÂøÊðÇÝæêé6)BFig. 3(a)Ìõdq­xÌ FEL pX­xË¶ÍCFig. 3

1)
2)
3)
4)
5)
6)
7)

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(b)É¦³ê½ 3 õq 2 dCI»ßöÉÎ·é[gûúËõ Sept. 2010 Vol.23 No.5  293 ÒÐî Fâ×³Våww©RÂ«ÈwÈÉy³ö
E­mail: hikoskaenv.sc.niigata­u.ac.jp
êåF´qªqÈwmªðn
1997NHÆåwHw¤Èm
ÛöC¹CmiwjBªqÈw¤
Cú{wpU»ïCIbNXtH[håwC¨¿\¢Èw¤ÅÌm¤õCªqÈw¤Éè/³ðoÄC2009N 9 æè»EBJäªqÈw¤ õªqÈwæOå³E­mail: fusitaniims.ac.jpêåFAgb¨æÑtFgb[U[pXðp¢½´qªqÌ´¬ªõmªðn
1997Nsåww»wêU²ÆC
2002Nsåwåw@w¤ÈmÛöC¹CmiwjC¯N x©RåwÀ±¨¤ ·úm¤õC2006NªqÈw¤ îbõÈw¤å èC2007Næè»EB

Hì¾h¼Ã®åwåw@w¤È¨¿wêUi»wnj³ö
E­mail: hishichem.nagoya­u.ac.jp
êåFõ¨»wC­[U[êÈwmªðn
1989NsåwHw¨HwÈ²C
1994N¯åwåw@Hw¤ÈmÛ
öC¹CHwmC¯Nåwåw@¶»¤ÈèC1997N¯åw@ w n ¤  È  è C 1998 N ¯ u t C1999N¯³öB2003N 4 ªqÈw2009N 3 ¤y³öC2005N10_³«ª¯¤õ±B2010N 4 æè
»EBMulti­photon multiple ionization of atoms irradiatedwith EUV SASE_FEL pulses
Yasumasa HIKOSAKA1 Mizuho FUSHITANI2,3 and Akiyoshi HISHIKAWA2,31Department of Environmental Science, Niigata University, Niigata 950_2181, Japan
2Institute for Molecular Science, Okazaki 444_8585, Japan

3Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya 462_8602, Japan

Abstract Multi­photon multiple ionization is a typical non­linear response of atoms in intense EUV laser
elds. Photoelectron spectroscopy utilizing with a magnetic­bottle­type electron spectroscopic technique is a
useful mean to study the details of multi­photon multiple ionization processes. We present that the method en­
ables us to monitor the uctuation of SASE_FEL spectra and to derive precisely photon energy dependences ofthe multi­photon multiple ionization processes.

294  úËõ Sept. 2010 Vol.23 No.5