Vanderlei S. BAGNATO Univ. de Sao Paulo, IFSC - Center for Optical Science & Photonics SP Sao Carlos Brazil

Size: px

Start display at page:

Download "Vanderlei S. BAGNATO Univ. de Sao Paulo, IFSC - Center for Optical Science & Photonics SP Sao Carlos Brazil"

Tamsin Susanna Stephens
6 years ago
Views:

1 JIUIL united nations educational, scientific and cultural organization the international centre for theoretical physics international atomic energy agency SMR WINTER SCHOOL ON LASER SPECTROSCOPY AND APPLICATIONS 19 February - 2 March 2001 COLD COLLISIONS AND CHEMICAL REACTION Vanderlei S. BAGNATO Univ. de Sao Paulo, IFSC - Center for Optical Science & Photonics SP Sao Carlos Brazil These are preliminary lecture notes, intended only for distribution to participants. strada costiera, II trieste italy - tel I I fax sci_info@ictp.trieste.it -

3 f ml con 300 -i id n < 920 x CL g 300 o 200 : IOO - 1,1, i if! III m 1 A» %3Q r 9ta 980.,,1 ij * ^ PkOBE L^SER FREQUENCY (cm*" 1 ) 920 FIG. 57. Phbtoafcsociatfte ion&atidri spectfunt of i^a collisions from the NIST dark-spot MOT, From Rafliff ii&l (l$94).

4 o.o OS 1.0!o.o u /,\\ :i *\ *i i» si SIVII 11 u J«n i of 7OO 11*00 ' H9OO II7OO TruTrrCiTuT n TTtrt s mrii.irruimi t ii irn n n U it 11 n n,n 11 it n Mini ii it i) a ;i :i it :i:t: t; 1: u ' I24OO "' LAStR FREQUCNCY <«*- I25OO Tr IG. 61. Photoassociation FORT trap-loss fhnorftscence sf>ectrum of Rb 2. From Miller et al <1993b). 1 i v ivntititii in mi I28I4-;, LASER ffrequency (cm* 1 ) JFlCi. 62. Cline et al. (1994a, 19946) separated the trapping and scanning functions-with [two different iasers: one laser at fixed frequency produced the J^ORT while a probe laser scanned through the resonances. V \V*\ G air Experiment Oaupp «f til. 7 ) Caiisson «f A/ 1» } This work Theory QluikioK ri ai \ c j Wflbr. 19 Piplrt /»/ /i' j 70 Cliufiq?i 1 bng of /»'.?'S \ Bninolt P».1M? «) :>? A?: r, LifntiTnO {nr>)

5 0 &\fa - UA ju 1> >0 +7c PfiOBE FREQUENCY-MBlibO ifc-t FIG. 59. High resolution photoassociatiyc ioiiiiatidn s^trum of rdtational levels associated With v-^ of the lohg-raiige 1, state of Na 2. Note residual hyperfirie splitting in the J = 2 iniet. From Ratliff rffl/. (1994)..' / orb.f: / V 3 r200 ~I2O -40 o a CO obi O.*; d.ol aoi'l -200 ~I2O -40 ^00 J^li20 r-40 PIG. 60. High resolution line profile measurements and theory on rotational progre'ssjofi-associalicki.wtth y = 48 of the longrange excited lj stateiofcna^ Frorti Napolitano et al (1994). ^ 'a w

6 / 0 = JSf t ^i;&lj&4i*&iil /

7 0.35 r [ vibratiohal level > 0.15 CO c. ' : S p.i6 fo 25 qx>5 CO 5 boo a. RO vtbrationdl / \ / y 75 / /" ' / 0 O) CO o CO o CO to CO o o CL 0.30 ois : % - -A BO - a* 24 j. ^-.37^ y 0 vibration*! level _/ / Z : U

8 ' " * * > - TABUS HI. Scattering Lengths - '.-V. LIU- u ' "Ai dt ±2-20 ±10 +40^ ± &# Ai_j : 'A3,-3 :At,-l/i;2 +52 ±5 V 85 Rb +^78±i ± ± «-* +po +25 '* +-^te +gl4i;i4 +2B6 361 "Abraham, et al. (1997) *Tiesinga; r et al. (1996) c Boesten, Vogels, et al. (1996) d C6t6,etal. (1997) e Boesteh, liai, et al. (1996) 'is&etml. (f9 i) +M^140 > ± ±5 46±12 h Amdl, etai (1993) % %

9 T boto OY\ * v Q/>^* c i 1 oyv Cc ^V octy >* I j o +e cf

10 !> + Oi 1600» Na* iiq a J S>! i1^ a n is w* s

11 bound state INTENSITY < *«FIG. 53. Photoassociative ionizaiion rate constant as a function of MOT light intensity. MOT laser detuned to tfce re^of resonance about one natural linewtdth. Frorn Bagnato, Marcassa, Wang, et al. (1993) t?o FiG. 52. Pliotoassociative ionization in Na collisions. From Heather and Julieflne (1993). HodeL L/ f

12 *" ' 'it ii m ^ *,...

13 U3 v CKV)d '\lou\y f (JU, e Mt/er

14 XOPQ " I $00 * OJeli SKXH ( 4o

15 oi f

16 IF-1? CoWh OF v?y«.pa. ) 4. )

17 ,. -r -..., I'!^ OP JE Ui 1 - -' ^ ' '" *i i^i UI > a: P-2- y. * a -2Q0O H 4000 FIG. 55. Two-color photo'assoeiatiye ionization. Inset shows MOT (u>{) and repurnpef. (w 2 ) fixed frequencies arid sweeping probe ((Op)^frequency. From Bagnato, Martassa, Tsao et ah (1993)., vv. tooy. ip~ O OOO FIG. 56. Two-color photbafisdciative ionization. Insets above features describe excitation routes. Frequencies are labeled as in the previous figure. Frorn^Bagnatbi Marcassa, Tsao, et al. (1993).

18 VIBRAT ION At. QUANtUM 1 NUMBER (v) Ions (arb. units) i 1 1 U

19 16o Ve p u f \/e a oe> a ) 7

20 \ a sea iocs L i+p fia) 6 -h a> p Re 2 lx L Re, 2+2

21 vw ri^deaxl Suppression Frequency V UP : m I % 1 IK -4000? -300p /-I'CjOO 'P 00 LA5EIR FREQUENCY (MHz) FIG. li. Effect of optical suppression oil the photoassociative ronization spectnijrfi ojbserved in a NaMOT. Solid curve isithe phqtoa^sbciative iqnization specttum withbut the supr3ressi6ii Afield oij pffeseiit Dotted curve shows thie photoassociative ionizatioh ip^ctrurh (o s present. Note enhancement of signal to the rignt oi u> s, suppression to the left. Note also the cutoff of the photoassociative ibnization signal to the left of co^ without the suppressiq^ field and the extension of this cutoff to &) 4 when xo s is present, f rbfh Marcassa et al. (1994). NQ2 p+p (o) I + 1 FIG. 76. Schematic of transitions showing photoassoeiative ionization and optical suppression df photoassociative ionization: (a) Two-step PAt process; (b) suppressor frequency o> 3 irnposed dn the coliisiph, rerouting incoming flux to the repulsive excited curve; (c) witrim p tuiied to the right of o> 3, phptoasiociative iomzation takes place with enhanced probability dime to addi^pn of to 3 and u> 4 to <& 2 - From Marcassa et al. (1994). l + l

23 CMJCH - X

24 tm Q INTENSITY (W/cm 2 ) Lt**6r (theory) Circular (theory) <t>) IO 10" Linear (expit) Circular (expt) I (W/cm 2 ) i(w/citt 2 )

25 r. -. i :. \.. : ; :.. i. ( \ \ J 1

26 IN <*. V I V c C CD 10 CO o CO b \ I f f J I 1 1 -^-- p --, J, b> : 1 - > CD OS UJ 2 Inelastic process (b), Inelostic ^ process IS+S) IS+S,N P > IS+P,N p -l> J $o(t?kj I NTERNUCL^AR

27 c] ~ ;M& fmi)] o ;0

28 IU I *% a s= 10a 0 i 1 \ " 1 i 2.0 y 15 i - Z 1:0 LJJ 0.5 / / 9 / m A A A ^'* AA}' ' ^» A, A' ^ * A J o:o i f 1V o(n)... t

29 A. eial - TK^a feu A.. A

I M P O R T A N T S A F E T Y I N S T R U C T I O N S W h e n u s i n g t h i s e l e c t r o n i c d e v i c e, b a s i c p r e c a u t i o n s s h o

I M P O R T A N T S A F E T Y I N S T R U C T I O N S W h e n u s i n g t h i s e l e c t r o n i c d e v i c e, b a s i c p r e c a u t i o n s s h o u l d a l w a y s b e t a k e n, i n c l u d f o l