storage ring measurements of the dissociative recombination of h 3 + : a closer look
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Storage ring measurements of the dissociative recombination of H 3 + : a closer look. Holger Kreckel University of Illinois at Urbana-Champaign. TSR Group. University of Illinois. Kyle N. Crabtree Brian A. Tom Benjamin J. McCall. Old ř ich Novotny* Annemieke Petrignani Max H. Berg - PowerPoint PPT PresentationTRANSCRIPT
Storage ring measurements of the dissociative recombination of H3
+: a closer look
Holger Kreckel University of Illinois at Urbana-Champaign
Kyle N. CrabtreeBrian A. TomBenjamin J. McCall
Oldřich Novotny*Annemieke PetrignaniMax H. BergDennis BingManfred GrieserClaude KrantzMichael Lestinsky*Mario B. MendesChristian NordhornRoland RepnowJulia StützelAndreas Wolf
TSRGroup
Universityof Illinois
Richard Thomas
StockholmUniversity
Henrik Buhr
WeizmannInstitute
*Columbia University, NY
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
H He
C N O Ne
Mg
Fe
Si S Ar
The relevance of H3+:
astronomer‘s periodic table
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
The relevance of H3+:
engine of interstellar chemistry
H3+ formation
H2 + c.r. H2++ e-
H2+ + H2 H3
+ + H
Proton-hop reactions
H3+ + X XH+ +H2
H 2
H 2+
C H 3+
C H 5+
C H 4
C H2 3+
C H2 2
C H3+
C H3 3+
C Hm n
C H+
C H 2+
N H2
+
H C O+
O H+
H O2+
H O3
+H O2
O H
C H C N H2 5
+
C H C N H3
+
C H N H3 2
+
H C N2
+
H C N
C H N H3 2
C H N H2
C H C N3
C H C N2 5
C H
C H C O3
+
C H O H3 2
+
C H C O2
C H O H3
H C OC H O H
C H O C H
2
2 5
3 3
C H2 5
+C H2 4
H C O2 3
+C O3
C H2
H C N3 3
+H C N3
H C N5
H C N7
H C N9
H C N11
C H3
C 4
+
C H4+
C H4 2+
C H4 3+
C H4
C H3 2
cosm ic ray
H 2N 2
C OO
H 2
H 2
e
e
e
ee
e
e
N
N H 3
H C N
C H C N3
e
C O
H O2
C H O H , e3
C
H 2
H 2
H 2
e
e
C H 3
+e
e eH C N
C+
e
C+
H 2
e eC
+
H 2H 2
e
C O
C
H
+
e
e
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Steady State: [H3+]
=
ke[e-][H2]
The enigma of H3+ in diffuse clouds
Cosmic ray ionization rate
DR rate coefficient
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
10-7
10-8
10-10
10-9
10-11
year1970 1990 20001980 2010
“Perceived” H3+ DR rate coefficient
Glosik et al.(2000-2009)Stat. & flow. afterglow
Adams, Smith,Alge(1984)Flow. afterglow
Adams, Smith (1987)Flow. afterglow
Amano (1988)IR spectroscopy
Larsson et al. (1993)Storage ring McCall et al. (2003)
Storage ring
Kreckel et al. (2005)
Storage ring
Leu, Biondi,Johnsen (1973)Stat. afterglow
H3+
DR
rat
e co
effic
ient
at
300K
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Storage ring measurements: concept
• radiative relaxation of internal excitations (rotation, vibration)
• direct measurement
• 100% detection efficiency
• high resolution
Advantages
Problem
H3+ !
• radiative relaxation incomplete
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
(1,00) theory
(2,00)theory
experimental data (T < 1ms)
experimental data (T > 2s)
(0,00) theory
Coulomb explosion results H3+
Kreckel et al., PRA 66, 052509 (2002)
Vibrations decay withinthe first 2s of storage
Some rotational statesstay forever
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
H2Gas inlet
2 atm
Solenoid valve
-900 Vring
electrode
Pinhole flange/ground
electrode
H3+
“Cold” ion sources
Supersonicexpansion
CRYRING 2002
5 cm
Cryogenic ion trap
TSR2004
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
● TSR electron temp. kT┴=0.5 meV ~ 6KkT||=25 μeV trap temp. 13 KKreckel, PRL 95, 263201 (2005)
● CRYRING kT┴= 2 meVion temp. 30-50 KMcCall, Nature 422, 500 (2003)
Storage ring results with “cold” H3+ ion sources
TheoryKokooulineand Greene
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
+
orthoI = 3/2
paraI = 1/2
+
The holy grail: state specific measurements
H3+
rotationallevels
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Nuclear spin effect: exp. and theory 2005
۰para H2
۰normal H2
experimentkT┴=4 meV
theoryGreene et al.
- para- ortho
Kreckel et. al, PRL 95, 263201 (2005)
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Theory with more accurate resonance energies
S. Fonseca dos Santos et al., JCP 127, 124309 2007
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Quantifying nuclear spin effects
B. Tom et al., JCP 130, 031101 2009
Reducedrate coeff.
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
skimmerdischarge electrode
pinhole
plunger
piezo actuator
locking nut
6 cm
high pressureH2 reservoir
low pressure
Piezo expansion source
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Cavity ring down measurements at UIUC
Difference frequency generation: 3.67 μm
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Transitions observed
HG
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Rotational temperature
pure H2 discharge, 2bar
Trot=110 K
1:5 H2:Argon discharge, 2bar
Trot=180 K
No vibrations found!
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Nuclear spin manipulation
1:5 n-H2 : Argon mixture p-H3+ fraction p3= (47.9 ± 2) %
1:5 p-H2 : Argon mixture p-H3+ fraction p3= (70.8 ± 2) %
ortho H3+ para H3
+ para H3+
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
UI Champaign-Urbana
MPI-K Heidelberg
DR measurements at TSR
Test Storage Ring
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Absolute scale of the rate coefficient
electron beamswitched off
electron target lengthstorage ring circumference
electrondensity
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Comparison to CRYRING 2002
CRYRING 2002 (n-H2)
TSR 2009 (n-H2:Ar 1:5)
1 m
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
H2+ + e-
beam vel.
Rotational temperature: imaging basics
d
2-dimensional imaging, point source
P(D)3-dimensional imaging, point source
d ~ √Ek
2-dimensional imaging, extended source
δtdetector
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
2-dimensional imaging of the 3-body breakup
H3+ + e- H + H + H
ne(cooler) = 1.4 x 107 cm-3
ne(target) = 1.34 x 106 cm-3
expectedKER = 4.79 eV
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
2-dimensional imaging of the 3-body breakup
950 K450 K200 K
rotational temperatures(uncertainties ~ 200 K)
H3+ + e- H + H + H
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Piezo source extraction potentials
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Conditions on-axis downstream of the nozzle
Collisional heating during Ion extraction?
skimmer
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Detailed comparison of the (reduced) rate coefficient
TSR / 22-pole trap 2007
CRYRING / Solenoid 2002
TSR / piezo 2009
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Nuclear spin dependence of the rate coefficient
1:5 n-H2 : Argon mixture
1:5 p-H2 : Argon mixture
p3= (47.9 ± 2) %p3= (70.8 ± 2) %
Extrapolation:100% ortho H3
+
100% para H3+
Reducedrate coeff.
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Summary• While we measure a rotational temperature of 200K with CRD spectroscopy,the stored H3
+ ions are much hotter than the ion source.
• We observed clear differences between different ion sources→ the heating is probably happening prior to injection into the ring .
• We observed for the first time detailed structures in the rate coefficients for ortho-H3
+ and para-H3+ at low energies.
The holy grail?
Still out there …
Results: Kreckel et al., submitted to PRAPetrignani et al., in preparation
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Perspectives:the case to continue the quest
Kyle N. Crabtree et al., to be published
It is crucial to understand:H3
+ + H2 andH3
+ (J=1,K=0,1) + e-
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look
Collaboration
Kyle N. CrabtreeBrian A. TomBenjamin J. McCall
Oldřich Novotny*Annemieke PetrignaniMax H. BergDennis BingManfred GrieserClaude KrantzMichael Lestinsky*Mario B. MendesChristian NordhornRoland RepnowJulia StützelAndreas Wolf
TSRGroup
Universityof Illinois
Richard Thomas
StockholmUniversity
Henrik Buhr
WeizmannInstitute
*Columbia University, NY
Funding: NationalScienceFoundation
Max-PlanckSociety
German-IsraeliFoundation
Eurppean Comission
DR 2010, Lake Tahoe, Aug19th 2010Holger Kreckel Storage ring measurements … of H3
+: a closer look