mm-wave rotational spectrum of methyl nitrate jessica thomas, ivan medvedev, department of physics,...
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MM-Wave Rotational Spectrum of Methyl Nitrate
Jessica Thomas, Ivan Medvedev, Department of Physics, Wright State University
David DolsonDepartment of Chemistry, Wright State University
• Chemical related to metabolism
• With diabetes this chemical has been known to be on the order of parts per trillion.
• Also, it is known to be expressed in breath in children with type 1 diabetes.
• Likely, oxidative stress on individuals during hyperglycemia in type 1 diabetics causes methyl nitrate production.
• Could be an indicator used for air quality monitoring
• Possesses explosive qualities
• Could be a molecule of interest in interstellar medium
OUR INTEREST IN METHYL NITRATE
http://commons.wikimedia.org/wiki/File:Methyl_nitrate_3D_ball.png
The synthesis of this chemical was done by scaling down and following the procedures published in Organic Syntheses. Our experiment was done to yield roughly 3-4 ml of MeONO2.
THE SYNTHESIS
Drying Setup
Glass Wool
CaCl2
3-4mL MeONO2
•Nitration of methanol by a mixture of sulfuric and nitric acid.
•Sulfuric acid is used as a catalyst and an absorber of water
•The product was dried to remove any excess water
http://commons.wikimedia.org/wiki/File:Methyl_nitrate_3D_ball.png
METHYL NITRATE, THE MOLECULE
Molecular Formula CH3NO3
Molar Mass 77.04 g/mol
Density 1.203 g/cm3
Melting point -82.3C
Dipole moment μa = 3.1 Dμb = .25 D
• Colorless volatile liquid
• Ignited, it burns with a gray-blue flame
• Toxic when inhaled
• Difficult to store for extended periods of time
PREVIOUS RESEARCH
Dixon, W., & Wilson JR, E. B. (1961, July 1). Microwave Spectrum of Methyl Nitrate. The Journal of Chemical Physics, 35, 191-198.
Parameter
A / MHz 11795.06
B / MHz 4707.52
C / MHz 3438.29
Ia / amu A2 42.8596
Ib/ amu A2 107.388
Ic/ amu A2 147.030
Ia+ Ib- Ic 3.218
ҡ -0.696239
This paper also discusses briefly the excited state of methyl nitrate.
SUBMILLIMETER ROTATIONAL SPECTRA OF METHYL NITRATE, Drouin, Brian J.; Zhang, Xu; Ellison, G. Barney, 2008, Columbus (400-440 GHz)
IF
VDI
Tran
smitt
er
VDI
Rece
iver
Absorption Cell: length - 2 m ,volume - 14 L
x24
SteppingSynthesizer
LO
Sidebandfilter
Computer
IF detectorLock in
SweepingSynthesizer
Gas Inlet
Absorption CellCustom Built Microwave
Synthesizer
Continuous Wave THz Spectrometer
Microwave Synthesizer
Custom Built
Diode Multipliers Virginia Diodes
Absorption Cell 2 m long by 4in wide (14 L)
OUR SYSTEM
THE SPECTRUM
•prolate asymmetric top with the moments of inertia along the three principle axes falling into the order IaIbIc.
•For asymmetric tops the allowed transitions all obey selection rules ∆J = 0, ±1 and the components of dipole moments dictate the transitions between Ka and Kc.
B
CA
•a-type transition has the selection rules ∆ Ka = 0(±2,±4) and ∆ Kc = ±1(±3,±5)
•b-type transition has the selection rules ∆ Ka = 1(±3,...) and ∆ Kc = ±1(±3,…)
Ground State
1st Excited State
GROUND STATE
265 lines assigned with J numbers ranging from 24 to 38
Parameter Current Valuea Previous ValueA / MHz 11795.12844(259) 11795.06
B / MHz 4707.57017( 78) 4707.52
C / MHz 3438.24379( 77) 3438.29
ΔJ / kHz 0.974760(295)
ΔJK / kHz 4.32862(109)
ΔK / kHz 4.4918(172)
δJ / kHz 0.249434(199)
δK / kHz 2.7136( 43)
Avg. / kHz .561 rms /kHz 56.967
NUMERICS
Parameter Old Values Current ValueA / MHz 11795.06 11795.12844(259)B / MHz 4707.52 4707.57017( 78))C / MHz 3438.29 3438.24379( 77)
Ia / amu A2 42.8596 42.85930438Ib/ amu A2 107.388 107.386822Ic/ amu A2 147.030 147.0317496
Ia+ Ib- Ic 3.218 3.214376799ҡ -0.696239 -0.696220199
1ST EXCITED STATE
1ST EXCITED STATE
Perturbed lines from likely a combination of the v=1 methyl torsion and the v=1 NO2 torsion.
Upper state: 30 6 25Lower state: 29 6 24a,q,R,30,-1
Upper state: 31 5 27Lower state: 30 5 26a,q,R,31,-1
Upper state: 28 8 20Lower state: 27 8 19a,q,R,28,0
Upper state: 31 4 27Lower state: 30 4 26a,q,R,31,0
Parameters Tentative Values
A / MHz 11760.80302(277)
B / MHz 4704.80082(147)
C / MHz 3442.22668(130)
AVG/ MHz -0.002452
RMS/MHz 1.048496
1ST EXCITED STATE
Upper state: 29 7 22Lower state: 28 7 21A,q,R,29,0
CONCLUSION AND STEPS FORWARD
This experiment assigned the ground state and offered a rough estimate of the assignment of first vibrational state between 210 -270. By doin so we were able to refined the rotational constants that were furnished by previous the microwave study of this molecule.
•Refine line lists•Work towards the assignment of the excited state•Extend assignment beyond 270 GHz
Goals: