Laboratory spectroscopy of H 3. Ben McCall Oka Ion Factory TM University of Chicago

Transcription

1 Laboraory specroscopy of H 3 + Oka Io Facory TM Uiversiy of Chicago

2 Moivaios Asroomical obai frequecies for deecio & use as probe Quaum Mechaical sudy srucure of his fudameal io refie heoreical calculaios of polyaomics

3 Formaio of H 3 + H 2 laboraory plasma iersellar medium e - impac H 2 Proo Affiiy: ~ 4.4 ev ~ 1 kcal/mol ~ D(H 2 ) H 2+ + H 2 H 3+ + H H 2 cosmic ray Rae cosa: k ~ cm 3 s -1 Exohermiciy: H ~ 1.7 ev

4 Laboraory Plasma

5 Types of Molecular Specroscopy Elecroic (visible) e e Poser: Friedrich & Alijah Roaioal (microwave) Vibraioal (ifrared)

6 Vibraioal Modes of H 3 + ν 2x ν 2y Ifrared iacive Ifrared acive Degeerae ay liear combiaio

7 Vibraioal Modes of H 3 + ν 2x ν 2y ν 2+ vibraioal agular momeum

8 Quaum Numbers for H 3 + Agular momeum I uclear spi J uclear moio» k = projecio of J ; K = k l 2 vibraio I=3/2 orho I=1/2 para l-resoace : saes wih same k-l 2 mixed G k-l 2 roaioal par of J Symmery requiremes G=3 orho, G 3 para Pauli: cerai levels forbidde (J=eve, G=)

9 The ν 2 fudameal bad ν 2 sae Eergy (cm -1 ) J (J,G) {u,l} Q(1,) R(1,) R(1,1) l R(1,1) u P(3,3) 6 groud sae Eergy (cm -1 ) G 2 3 orho para G para orho

10 Experimeal work o ν 2 Iiial Deecio (Oka 198) search over wo years, over 5 cm lies, few perce deep assiged by Waso overigh ν 2 = 2521 cm Oka 1981 Waso e al Majewski e al Nakaaga e al. 199 Majewski e al McKellar & Waso 1998 FTIR absorpio FTIR emissio FTIR absorpio wide-bad J=9 113 J= Oka 198 Uy e al Joo e al. 2 Lidsay e al. 2 FTIR emissio Lowes frequecy cm -1 Coiuous sca 3 36 cm -1 15

11 The ν 2 bad as a probe of H 3 + Laboraory H 3+ elecro recombiaio rae (Amao 1988) spi coversio of H 3+ i reacios (Uy e al. 1997) ambipolar diffusio i plasmas (Lidsay, poser) Asroomy probe of plaeary ioospheres (Coerey, Miller) cofirmaio of iersellar chemisry (Herbs) measuremes of iersellar clouds (Geballe)

12 The fudameal bad Relaive Iesiy P(J) uu Spacig illusraes large roaioal cosas (B ~ 44 cm -1 ) 2:1 iesiy raios reflec spi saisical weighs (orho/para) Q Q R(J) l l R(J) u R(J) u No R() lie hree equivale spi 1/2 fermios equilaeral riagle geomery Frequecy (cm -1 ) T=4 K

13 Udersadig he ν 2 Specrum For low eergies, use perurbaio approach: E = BJ(J+1) + (C-B)K 2 -D JK J(J+1)K E = ν 2 + B J (J +1) + (C -B )K 2-2ζC K l +... use observed rasiios o fi molecular cosas For higher vibraioal eergies, his approach compleely breaks dow Variaioal calculaios based o a ab iiio poeial eergy surface!

14 Variaioal Calculaios +4ν ν 2 5ν 2 3 +ν ν ν 2 4ν ν 2 +2ν 2 3ν 2 Eergy (cm -1 ) 5 2ν 2 +ν 2 2 ν 2 Zero Poi Vibraioal Eergy R θ R θ(rad)

15 Vibraioal Bad Types +4ν ν 2 5ν 2 3 +ν ν ν 2 4ν ν 2 +2ν 2 3ν 2 Eergy (cm -1 ) Overoes: ν 2 5 Ho bad: 2ν 2 ν 2 2ν 2 2 +ν 2 Combiaio: + 2ν 2 ν 2 Fudameal: ν 2 Forbidde: θ(rad)

16 Vibraioal Overview 1 ν 2 2ν 2.1 Relaive Iesiy.1 2ν 2 ν 2 3ν 2 +2ν 2 4ν 2.1 ν 2 +ν 2 3ν 2 ν 2 +ν 2 2 +ν 2 5ν Frequecy (cm -1 ) 8 1

17 Vibraioal Overview 1.1 ν 2 FCL (3 mw) Diodes (8 mw) 2ν 2 D.F. (LiNbO 3 ) (.1 mw) Ti:Sapphire (1 W) Relaive Iesiy.1 2ν 2 ν 2 D.F. (LiIO 3 ) (2 µw) 3ν 2 +2ν 2 4ν 2.1 ν 2 +ν 2 3ν 2 ν 2 +ν 2 2 +ν 2 5ν Frequecy (cm -1 ) 8 1

18 Vibraioal Overview 1.1 ν 2 FCL (3 mw) Diodes (8 mw) 2ν 2 D.F. (LiNbO 3 ) (.1 mw) Ti:Sapphire (1 W) Relaive Iesiy.1 2ν 2 ν 2 D.F. (LiIO 3 ) (2 µw) 3ν 2 +2ν 2 4ν 2.1 ν 2 +ν 2 3ν 2 ν 2 +ν 2 2 +ν 2 5ν Frequecy (cm -1 ) 8 1

19 Ho Bads A 6 K, ~2 imes weaker ha fudameal He domiaed discharge oly 5 imes weaker Bawedi e al. (199) 72 lies of 2ν 22 ν 2 +ν 2 2ν 2 14 lies of 2ν 2 ν 2 21 lies of +ν 2 ν 2 Variaioal calculaios esseial i assigme Sucliffe 1983; Miller & Teyso 1988, 1989

20 Firs Overoe Bad: 2ν 2 Firs overoe (2ν 2 ) usually orders of magiude weaker ha fudameal I H 3+, oly abou 7 imes weaker Discovery: (i hidsigh) Majewski e al. (1987) Jupier (Trafo e al. 1989, Drossar e al. 1989) Assiged by Waso (wih aid of ho bads) Majewski e al. (1989) 47 rasiios, FTIR Xu e al. (199) rasiios observed i absorpio 2ν 2 ν 2

21 Absolue Eergy Levels Fudameal: G = 2ν Q(1,1) Ho bads: G = Overoe bad: G = ±3 ( G = -3, G = +3) ν 2 1 P(2,1) P(2,2) Absolue eergy levels 2 1 G= G=1 G=2 G=3 E 12

22 Secod Overoe Bad: 3ν 2 ~ 2 imes weaker ha fudameal Bad origi ~ 7 cm -1 Tuable diode lasers Lee e al. (1991), Verudo e al. (1994) 15 rasiios observed 3ν 2 2ν 2 ν 2 Assiged based o variaioal calculaios Miller & Teyso (1988, 1989)

23 Forbidde Bad mode oally symmeric ifrared iacive very forbidde sice & ν 2 o coupled Firs mixig erm: Birss resoace mixes levels i & ν 2 wih same J, G=3 effecive for accideal degeeracies (fairly high J) Xu e al. (1992) 9 lies ν 2 sae J=5 J=5 sae G=2 G=5 = 3178 cm -1 Lidsay e al. (2) 1 ew lies J=4 groud sae

24 Forbidde Bad +ν 2 ν 2 No as forbidde as aharmoiciy of poeial mixes +ν 2 wih oher saes (e.g. 2ν 22 ) +ν 2 ν 2 ca borrow iesiy from allowed bads (e.g. 2ν 22 ν 2 ) +ν 2 2ν 2 Xu e al. (1992) observed 21 lies ν 2

25 Combiaio Bads +2ν 22 +2ν 2 3ν 2 Highes eergy bad Weakes allowed bad 2ν 2 +ν 2 27 imes weaker ha ν 2 Tuable diode laser cm -1 ν 2

26 Observed Specrum 1. Q(1,) R(1,).8 R(3,3) 28 rasiios of +2ν 22 Relaive Iesiy.6.4 R(2,2) P(3,3) R(1,1).2 P(2,2) Q(3,) P(1,1) l P(4,4) Q(1,1) R(2,1) Q(2,1) R(3,) R(4,3) R(3,2) Q(2,2) Q(3,3) u R(1,1) Q(3,2) 2 of 2 +ν 21 P(6,6) P(5,5) Frequecy (cm -1 ) 81

27 Table of Resuls Symbol Obs Calc o-c J' <G'> ± o/p ' <v1'> <v2'> <l2'> J" k" Q(3,) o Q(1,) o R(3,3) o P(1,1) p P(2,2) p R(2,2) p P(3,3) o P(4,4) l p R(1,1) p R(4,3) o Q(1,1) p Q(2,1) p Q(3,1) p R(3,2) p R(2,1) p R(1,) o Q(2,2) p R(4,2) p Q(3,2) u p Q(4,2) u p R(3,1) p R(3,1) l p P(6,6) o R(1,1) p Q(4,3) o Q(3,3) o P(5,5) p R(4,1) p R(2,1) p R(3,) o Predicios from J. K. G. Waso

28 Table of Resuls Symbol Obs Calc o-c J' <G'> ± o/p ' <v1'> <v2'> <l2'> J" k" Q(3,) o Q(1,) o R(3,3) o P(1,1) p P(2,2) p R(2,2) p P(3,3) o P(4,4) l p R(1,1) p R(4,3) o Q(1,1) p Q(2,1) p Q(3,1) p R(3,2) p R(2,1) p R(1,) o Q(2,2) p R(4,2) p Q(3,2) u p Q(4,2) u p R(3,1) p R(3,1) l p P(6,6) o R(1,1) p Q(4,3) o Q(3,3) o P(5,5) p R(4,1) p R(2,1) p R(3,) o Predicios from J. K. G. Waso

29 +2ν 22 Eergy Levels J G* Upper Sae Eergy (cm -1 ) <l 2 > <G>

30 Breakig he Barrier o Lieariy +4ν ν 2 5ν 2 3 +ν 2 Eergy (cm -1 ) 1 5 4ν 2 3ν 2 2ν 2 ν 2 +3ν 2 +2ν 2 +ν ν 2 2 +ν θ(rad)

31 Fuure Prospecs Improvemes i Theory Hyperspherical coordiaes for lieariy (Waso) Relaivisic effecs (Jaque) No-adiabaic effecs (Polyasky & Teyso 1999) Experimeal Advaces Tiaium:Sapphire laser, Dye laser New echiques (heerodye, caviies?) 4ν 2, 5ν 2 o he horizo... 1ν 2 i he fuure??

32 Ackowledgemes Oka J. K. G. Waso Faie ad Joh Herz Foudaio NSF NASA

33 Colum Desiy of H 3 + (coceraio) (pah legh) Colum Desiy Laboraory: 1 11 cm cm = 1 14 cm -2 Molecular Cloud: 1-4 cm cm = 1 14 cm -2 Laboraory ad asroomical specroscopy progressig ogeher!