scholarly journals Time-Resolved Infrared Spectroscopy in Supercritical Fluids

1999 ◽  
Vol 19 (1-4) ◽  
pp. 133-139 ◽  
Author(s):  
Michael W. George ◽  
Martyn Poliakoff ◽  
Xue-Zhong Sun ◽  
David C. Grills
Keyword(s):  
Infrared Spectroscopy ◽  
Supercritical Fluids ◽  
Room Temperature ◽  
Noble Gas ◽  
Fast Time ◽  
Metal Carbonyls ◽  
Time Resolved ◽  
Organometallic Reactions ◽  
Time Resolved Infrared Spectroscopy ◽  
First Time

We have used fast Time-resolved Infrared Spectroscopy (TRIR) to probe organometallic reactions in supercritical fluids on the nanosecond time-scale. This has allowed us to identify, for the first time in solution at room temperature, organometallic noble gas complexes which are formed following irradiation of metal carbonyls in supercritical noble gas solution. We have found that these complexes are surprisingly stable and have comparable reactivity to organometallic alkane complexes. We have also studied the coordination of CO2 to metal centres in supercritical CO2 (scCO2) and provide the first evidence for the formation and reactivity of ɳ1-O bound metal CO2 complexes in solution at or above room temperature.

Setting Kinetics Observation of a Brushite Cement by FTIR and DSC

2006 ◽  
Vol 309-311 ◽  
pp. 837-840 ◽  
Author(s):  
M.P. Hofmann ◽  
A.M. Young ◽  
Showan N. Nazhat ◽  
Uwe Gbureck ◽  
J.E. Barralet
Keyword(s):  
Differential Scanning Calorimetry ◽  
Infrared Spectroscopy ◽  
Calcium Phosphate ◽  
Chemical Reaction ◽  
Calcium Phosphate Cement ◽  
Scanning Calorimetry ◽  
Time Resolved ◽  
Setting Reaction ◽  
Time Resolved Infrared Spectroscopy ◽  
First Time

Time resolved infrared spectroscopy (FTIR) and isothermal differential scanning calorimetry (DSC) were used for the first time to monitor the chemical reaction in a fast setting brushite forming calcium phosphate cement. It was found that the reaction percentage at a given time was dependent on temperature and not powder to liquid (P/L) ratio. Both methods showed that there was, within the temperature range investigated, a single autocatalytic like setting reaction within the cement paste. Final conversion of the reactants was found to be unaffected by temperature and P/L ratio.

Organometallic alkane and noble-gas complexes in conventional and supercritical fluids

2001 ◽  
Vol 73 (3) ◽  
pp. 443-447 ◽  
Author(s):  
Gavin I. Childs ◽  
David C. Grills ◽  
Xue Z. Sun ◽  
Michael W. George
Keyword(s):  
Ambient Temperature ◽  
Supercritical Fluids ◽  
Noble Gas ◽  
Fast Time ◽  
Time Resolved ◽  
Wide Range

Fast time-resolved infrared (TRIR) spectroscopy has been used to study a wide range of organometallic alkane and noble-gas complexes at ambient temperature. We have shown that the reactivity of the n-heptane complexes decreases both across and down Groups V, VI, and VII, and that the corresponding xenon complexes have similar reactivities.

scholarly journals Excited States and Intermediates by Time-Resolved Infrared Spectroscopy

1999 ◽  
Vol 19 (1-4) ◽  
pp. 245-251 ◽  
Author(s):  
J. J. Turner ◽  
M. W. George ◽  
I. P. Clark ◽  
I. G. Virrels
Keyword(s):  
Infrared Spectroscopy ◽  
Excited State ◽  
Charge Transfer ◽  
Excited States ◽  
Fast Time ◽  
Time Resolved ◽  
Excited Species ◽  
Charge Transfer Transitions ◽  
Time Resolved Infrared Spectroscopy ◽  
Kinetics Of

For coordination compounds containing CO or CN groups, fast time-resolved infrared spectroscopy (TRIR) provides a convenient method of probing excited states and intermediates. TRIR has proved particularly powerful for probing the structure and kinetics of organometallic intermediates. The interpretation is particularly straightforward when combined with IR data from matrix isolation experiments, although there can be some subtle differences. In excited state studies, shifts in ν(CO) and ν(CN) frequencies, from ground to excited state, are sensitive to the changes in electron distribution on excitation, thus allowing the distinction between charge-transfer and non-charge-transfer transitions. Subtle effects on excited state ν(CO) band positions occur with change from fluid to rigid solvent-“infrared rigidochromism”. There is often a change in ν(CO) band width on excitation; this can be interpreted in terms of specific interactions between the excited species and the solvent. This paper presents some of our recent work in this area.

Recent advances in organometallic alkane and noble gas complexes

2009 ◽  
Vol 81 (9) ◽  
pp. 1667-1675 ◽  
Author(s):  
James A. Calladine ◽  
Khuong Q. Vuong ◽  
Xue Z. Sun ◽  
Michael W. George
Keyword(s):  
Nmr Spectroscopy ◽  
Room Temperature ◽  
Noble Gas ◽  
Metal Carbonyl ◽  
Fast Time ◽  
Time Resolved ◽  
New Approach ◽  
Metal Centers ◽  
Wide Range ◽  
Metal Ligand

Fast time-resolved infrared (TRIR) spectroscopy has been useful for studying the reactions of a wide range of organometallic alkane and noble gas complexes at ambient temperature following irradiation of metal carbonyl precursor complexes. The reactivity of organometallic alkane and xenon complexes decreases both across and down groups V, VI, and VII, and for a given metal/ligand combination the alkane and xenon complexes have similar reactivities. Systematic studies of reactivity have produced long-lived Re complexes which have allowed such complexes to be characterized using NMR spectroscopy. A new approach using liquid propane at low temperature as a solvent to monitor the interaction of such weakly coordinating ligands with transition-metal centers is outlined. TRIR studies monitoring the coordination and activation of methane and ethane in supercritical methane and liquid ethane solvents at room temperature are also reviewed.

scholarly journals Calculating singlet excited states: Comparison with fast time-resolved infrared spectroscopy of coumarins

2015 ◽  
Vol 142 (15) ◽  
pp. 154119 ◽  
Author(s):  
Magnus W. D. Hanson-Heine ◽  
Alisdair Wriglesworth ◽  
Maliha Uroos ◽  
James A. Calladine ◽  
Thomas S. Murphy ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Excited States ◽  
Fast Time ◽  
Time Resolved ◽  
Time Resolved Infrared Spectroscopy
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