T-Jump/FT-IR Spectroscopy: A New Entry into the Rapid, Isothermal Pyrolysis Chemistry of Solids and Liquids

1992 ◽  
Vol 46 (6) ◽  
pp. 900-911 ◽  
Author(s):  
T. B. Brill ◽  
P. J. Brush ◽  
K. J. James ◽  
J. E. Shepherd ◽  
K. J. Pfeiffer
Keyword(s):  
Thin Film ◽  
Ir Spectroscopy ◽  
Bulk Material ◽  
Control Unit ◽  
Control Voltage ◽  
Near Surface ◽  
Rapid Scan ◽  
Gas Products ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

The interface of a Pt filament pyrolysis control unit and a rapid-scan FT-IR spectrometer is described that enables the thermal decomposition of a thin film of material to be studied isothermally after heating at 2000°C/s. A model of the heat transfer of the Pt filament as a function of gas atmosphere and pressure is developed to help understand the instrument response. The control voltage of the Pt filament is highly sensitive to the thermochemistry of the thin film of sample. By simultaneously recording the control voltage and the rapid-scan IR spectra of the near-surface gas products, one learns considerable detail about chemical mechanisms relevant to combustion of a bulk material. The application of T-jump/FT-IR spectroscopy is illustrated with rapid thermolysis data for the energetic organoazide polymers azidomethyl-methyloxetane (AMMO), bis(azidomethyl)oxetane (BAMO), and glycidylazide polymer (GAP); the cyclic nitramine, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazacine (HMX); and the nitroaromatic 1,3,5-triamino-2,4,6-trinitrobenzene (TATB).

Thermal Decomposition of Energetic Materials 70: Kinetics of Organic Peroxide Decomposition Derived from the Filament Control Voltage of T-Jump/FT-IR Spectroscopy

1997 ◽  
Vol 51 (3) ◽  
pp. 423-427 ◽  
Author(s):  
G. K. Williams ◽  
T. B. Brill
Keyword(s):  
Ir Spectroscopy ◽  
Energetic Materials ◽  
Rapid Heating ◽  
Organic Peroxide ◽  
Control Voltage ◽  
Isokinetic Temperature ◽  
Kinetic Measurements ◽  
Rate Determining Step ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

An evaluation is made about whether T-jump/FT-IR spectroscopy can be used to determine the decomposition kinetics (Arrhenius Ea and ln A parameters) of energetic organic peroxides at high temperature following very rapid heating. Polystyrene peroxide (PSP) and benzoyl peroxide were investigated, but PSP was chosen for detailed study because of its known, simple, decomposition process. The shape of the control voltage trace of the Pt filament yields kinetic constants which are reasonable for O–O bond homolysis as the rate-determining step: Ea = 39 kcal/mol, ln ( A, s−1) = 45.9. These Arrhenius parameters differ from values measured by other methods, but it is found that an isokinetic temperature of 400 ± 20 K exists for all measurements. Thus, all the kinetic measurements appear to reflect the same dominant process (O–O homolysis), but their differences make extrapolation of the rates from the temperature range of measurement to another range inaccurate.

Applications of Time-Resolved Step-Scan and Rapid-Scan FT-IR Spectroscopy: Dynamics from Ten Seconds to Ten Nanoseconds

1993 ◽  
Vol 47 (9) ◽  
pp. 1376-1381 ◽  
Author(s):  
T. J. Johnson ◽  
A. Simon ◽  
J. M. Weil ◽  
G. W. Harris
Keyword(s):  
Fourier Transform ◽  
Ir Spectroscopy ◽  
Time Resolved ◽  
Time Resolved Spectroscopy ◽  
Rapid Scan ◽  
Scan Time ◽  
Ft Ir ◽  
Complementary Nature ◽  
New Applications ◽  
Ft Ir Spectroscopy

The step-scan technique in Fourier transform infrared (FT-IR) spectroscopy is employed in new applications of time resolved spectroscopy (TRS). Results are demonstrated on time-resolved laser emissions and photolytically generated chemical reactions using both emission and absorption modes. New achievements in FT-IR temporal resolution are demonstrated, as well as the complementary nature of step-scan and rapid-scan time-resolved spectroscopy.

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