Juraj Varga - Prof. Per Jensen, Ph.D.

Juraj Varga
FSO 3 • radical measurements and improvements of our spectrometer
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

Laboratory of High Resolution Molecular Spectroscopy
Prague
‣ QUASAAR fellow from the 1 st January 2007 in the Laboratory of High Resolution Molecular
Spectroscopy in Prague
‣ research activities of the laboratory - high resolution spectroscopy in microwave spectral region
of radicals and halogen containing molecules of an atmospheric importance i
and their
theoretical analysis → extremely accurate molecular structure and electrodynamical parameters
‣ measurement of precise ground state rotational frequencies of stable molecules - CH 3 Br and
radicals FCO 2 •,, FSO 3 •
‣ L. Kolesniková, , J. Varga, H. Beckers, , M. Šimečková, , Z. Zelinger, , L. Nová Střítesk
teská, , P. Kania, , H. Willner, and Š.
Urban: Detailed study of fine and hyperfine structures in rotational spectra of the free fluoroformyloxyl radical
FCO2, J. Chem. Phys. . 128, 1-8, 1
(2008).
‣ L. Kolesniková, , J. Varga, L. Nová Střítesk
teská, , H. Beckers, , H. Wilner, , F. Aubke, and Š. . Urban: The Ground State
Rotational Spectrum of the Fluorosulfate Radical, , J. Chem. Phys.,
Accepted 2009.
‣ improvement of measurements - development of the different modulation systems – Stark and
Zeeman modulation
‣ other experiments – multireflexion cell for weak transitions, Fabry-Perot resonator for low
frequencies (2-50 GHz)
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

Laboratory of High Resolution Molecular Spectroscopy
Prague
The Prague millimeterwave spectrometer setup with the pyrolysis device for radical measurements.
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

FSO 3
• radical
‣ the fluorosulfate radical – open shell system with one unpair electron → primarily causes a fine
splitting of the rotational levels into two sublevels – eletron spin-rotational interaction
‣ magnetic hyperfine interactions between the magnetic moments of the open shell electron
system and the 19 F nucleus as well as nuclear spin-rotational interaction → additional hyperfine
doubling of levels – very small, in rotational spectra nearly unresolved
‣ radical was produced by a low pressure pyrolysis of the bis(fluorosulfuryl)peroxide (430 K,
sample pressure of the equilibrium mixture was 6 ubar)
FSO 2 O-OSOOSO 2 F ↔ 2 FSO3•
‣ measurements spectral range – 93-281 GHz, frequency modulation with the second harmonic
lock-in detection
‣ measured in its vibronic ground state, more than 250 fine rotational transitions have been
en
observed, analyzed in detail using the matrix elements of the rotational, fine and hyperfine
Hamiltonian terms – observed, identified and analyzed for the first time
‣ derived very precise values of the rotational, centrifugal distorsion and fine constants and the
C 3v molecular symetry of the vibronic ground state was unambigously confirmed
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

FSO 3
• radical
0.0007
0.0006
0.0005
0.0004
0.0003
intensity [a.u.]
0.0002
0.0001
0.0000
-0.0001
-0.0002
-0.0003
-0.0004
-0.0005
270000 272000 274000 276000 278000 280000
frequency [MHz]
10 GHz overview with 150 MHz step – ~ 1000 lines, ~ 30 belongs to FSO3• radical
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

FSO 3
• radical
0.00004
intensity [a.u.]
0.00000
269970 270000 270030
frequency [MHz]
Example of the spectrum of fluorosulfate radical rotational transition N’ ← N” =26← 25
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

FSO 3
• radical
The radical and nonradical spectra measured with and without the magnetic field: a) the radical
lines are broadened and their peak heights are decreased because of the molecular Zeeman
Effect; b) the lines of the closed shell molecules are unaffected by the magnetic field and both the
spectrum traces are completely overlapped
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

FSO 3
• radical
The simple Loomis–Wood diagram indicates the assignments of the radical transition lines to rotational and
electron spin quantum numbers. The two groups of points for a given upper N’ quantum number correspond to
different values of ms = ±½ and thus to different components of the fine splitting. For some of these groups, the
highest possible K values are indicated.
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

FSO 3
• radical
The parts of the radical spectrum with transitions from energy
levels with the quantum numbers N” = 19 in the vibronic ground
state corresponding to the row with N’ = 20 of the Loomis–Wood
diagram
An illustration of the resolved hyperfine
splitting in the fluorosulfate radical rotational
transition N’ ← N” =10← 9.
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

FSO 3
• radical
The molecular parameters of the fluorosulfate radical in the vibronic ground state a,b,c .
Parameter
without hyperfine splitting
with hyperfine splitting
B
5195.528365 (259)
5195.528364 (291)
D N
×10 3 3.76291 (60)
3.76287 (64)
D NK
×10 3 −1.28189 (131)
−1.28162 (183)
H N
×10 9 −6.75 (44)
−6.83 (46)
H NK
×10 6 0.18816 (127)
0.18872 (156)
H KN
×10 6 −0.34627 (194)
−0.34765 (307)
h 3
×10 9 6.640 (21) b
6.640 (21) b
ε aa
−37.372 (59)
−37.344 (67)
ε bb
−271.9178 (189)
−271.8446 (265)
D S N ×103 −0.9931 (73)
−1.0123 (90)
D S NK
−0.0696 (188)
−0.0616 (228)
D S KN
0.0725 (190)
0.0646 (230)
D S K ×103 −1.628 (275)
−1.58 (37)
a F
…
−24.1 (45)
1.5 T aa
…
−2.628 (288)
s c 0.014
0.014
a All the data are in MHz. The numbers in parentheses
are standard deviations in the units of the last decimal
digit. The frequencies of the K = 3 doublets are
averaged.
b Fitted separately.
c The symbol s denotes a standard deviation of the fit.
‣L.
Kolesniková, , J. Varga, L. Nová Střítesk
teská, , H. Beckers, , H.
Wilner, , F. Aubke, and Š. . Urban: The Ground State Rotational
Spectrum of the Fluorosulfate Radical, , J. Chem. Phys.,
Accepted 2009.
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

Stark modulation
f [kHz]
U in [V]
1
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
44
46
50
3150
3100
3050
3000
2900
2740
2600
2450
2400
2400
2400
2400
2370
2350
2200
1800
1250
1100
1075
1000
1000
1000
1000
975
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

Zeeman modulation
Modulation frequency 0.5 – 3 kHz, magnetic field 4 mT
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

Acknowledgement
‣ Marie Curie Research Training Network (QUASAAR)
‣ Prof. RNDr. Štěpán Urban, CSc. as my supervisor
‣ all collaborating laboratories: Wuppertal - prof. Willner group, CTU Prague
QUASAAR Winter School, February 20-25, 25, 2009 Demänovsk
novská Dolina - Jasná, , Slovakia

Laboratory of High Resolution Molecular Spectroscopy
Prague
Prof. RNDr. Štěpán Urban, CSc.
Ing. Lucie Nová – Stříteská, PhD.
Ing. Lucie Kolesníková
Ing. Patrik Kania, PhD.
Ing. Jindřich Koubek
Michal Rybníček
Mgr. Tereza Uhlíková, PhD.
juraj.varga@vscht.cz
http://www.vscht.cz/anl/lmsvr/

Thank you for your attention.