Related Manuals for Vernier VSP-FP
Summary of Contents for Vernier VSP-FP
- Page 1 Vernier Flash Photolysis Spectrometer (order code: VSP-FP) Educational Flash Photolysis Spectrometer Reference Manual (version: 12/14/2015) © Ultrafast Systems LLC/Vernier Software & Technology...
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Page 2: Table Of Contents
Determination of the Activation Energy of the Thermal Back Reaction of One Spiropyran in Toluene ............................34 Appendix ............................... 38 Spectra of Flash Lamp and White Light LED ................38 Spectra of Optical Filters ....................... 40 © Ultrafast Systems LLC/Vernier Software & Technology... - Page 3 List of Figures Figure 1: Examples of Vernier Flash Photolysis Spectrometer data ............5 Figure 2: Detector responsivity vs. wavelength ................... 7 Figure 3: Schematic of the Vernier Flash Photolysis Spectrometer ............10 Figure 4: Screenshot of Vernier Flash Photolysis Spectrometer Software ..........13 Figure 5: Concentration time profiles of reactant and product ..............
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Page 4: General Information
Chemical change can be induced in a variety of ways—the one employed in the Vernier Flash Photolysis Spectrometer is by absorption of light. Thus the instrument serves also as a way of introducing the student to the concepts and practice of photochemistry. -
Page 5: Figure 1: Examples Of Vernier Flash Photolysis Spectrometer Data
Subsequent data processing, such as conversion of the acquired voltage waveform into temporal profile of ∆A and fitting the ∆A profile to an appropriate function in order to extract the rate constants, can be done by exporting the data into Vernier Logger Pro ®... -
Page 6: Equipment Specifications
Voltage range: 100–120 V & 210–240 V Frequency range: 50 Hz & 60 Hz Power rating: 50 W maximum DC battery: A23 12 V USB cable: 28 AWG shielded AC power cable: 18 AWG 300 V © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 7: Detector Specifications
λp 970 nm Rise time 14 ns Bias voltage 10 V Dark current (with 1 MΩ load) 0.35 nA Output voltage VOUT 0 to 10 V Figure 2: Detector responsivity vs. wavelength © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 8: Safety Information
Safety Information The Vernier Flash Photolysis Spectrometer is designed and manufactured for kinetic analysis of a chemical specimen by means of transient absorption spectrometry. It is not sold, nor intended for, nor should ever be used for any other purpose. The product should be used solely in accordance with the instructions provided. - Page 9 WARNING Situation has the potential to cause bodily harm or death. CAUTION Situation has the potential to cause damage to property or equipment. NOTE Additional information the user or operator should consider. © Ultrafast Systems LLC /Vernier Software & Technology...
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Page 10: Layout And Basic Principles Of Operation
Layout and Basic Principles of Operation Xe flash lamp Detector photodiode Sample Digitizer Figure 3: Schematic of the Vernier Flash Photolysis Spectrometer © Ultrafast Systems LLC /Vernier Software & Technology... - Page 11 LED light passing through the sample. These changes are detected by the monitoring photodiode. The output voltage waveform from the photodiode is collected and digitized by an internal DAQ device and transferred to the computer for further manipulation. © Ultrafast Systems LLC /Vernier Software & Technology...
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Page 12: Hardware Description
Hardware Description Turning the Spectrometer On and Off Connect the power cord to the AC input located at the rear of the Vernier Flash Photolysis Spectrometer. Connect the Vernier Flash Photolysis Spectrometer to the computer via a USB cable. -
Page 13: Software Description
A typical I should not be larger than 2 V for absorption measurements. If the values are lower than 500 mV or higher than 2000 mV, please contact Vernier Technical Support. For emission measurements, the LED light turns off and the I value should drop close to zero (<10 mV). -
Page 14: Graph Controls
Select X region to zoom in, keep Y limits unchanged. Default, select Y region to zoom in, keep X limits unchanged. Autoscale both x- and y-axes once to fit graph. Zoom in; Zoom out. © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 15: The Basic Principles Of Chemical Kinetics
In the (elementary) reaction Equation 1 The rate (change in concentration as a function of time) is expressed in the form of a derivative Rate = Equation 2 © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 16: The Rate Expression And The Rate Constant
This equation tells us that since the concentrations of the reactants decrease during the course of the reaction, then the rate (but not the rate constant) decreases with time © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 17: Order Of Reaction
These are not considered here because of lack of relevance to the Vernier Flash Photolysis Spectrometer concept. SPECIAL NOTE: It is important to realize that assignment of order by inspection is only valid for elementary reactions;... -
Page 18: The Experimental Approach
The Relationships Between Rate Constant, Half Life, and Life Time First, we shall consider a first order reaction symbolized by products The rate of this reaction is as written in Equation 9 as © Ultrafast Systems LLC /Vernier Software & Technology... - Page 19 At first sight, we would expect this process to show second order kinetics overall, but, as we shall see, the order actually observed in an experiment will be determined by the reaction conditions. © Ultrafast Systems LLC /Vernier Software & Technology...
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Page 20: Pseudo Order
This behavior can be detected by evaluating the first order rate constant at different initial concentrations of B, when the behavior will be found to depend linearly on [B]. © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 21: Data Treatment
Data Treatment Data Acquisition The Vernier Flash Photolysis Spectrometer Software will produce a file containing two columns of numbers in CSV format. One column (#1) is time, the other (#2) is voltage from the detector. On the computer screen, you will observe the waveform built from these columns. These are your raw data. -
Page 22: Figure 7: Time And Voltage (Raw Data) And Absorbance (Calculated)
3 (‘ΔA’). Logger Pro allows you to do this by creating a calculated column. After having done this, you can generate and display an absorbance vs. time graph. © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 23: Kinetic Analysis
The light-generated species in the suggested experiments are formed on a time scale much shorter than response time of the Vernier Flash Photolysis Spectrometer (~100 microseconds). Therefore we are only interested in studying the decay part of kinetic profiles. One important thing to consider when analyzing the kinetic profiles acquired with Vernier Flash Photolysis Spectrometer is the scattered excitation light recorded by the photodetector (Figure 8). -
Page 24: Figure 9: Absorption (Left) And Emission (Right) Kinetic Profilesincluding The Scattered Excitation Light Picked Up By The Detector
Logger Pro, the requirement for the fitting transform is to express the absorbance as a function of time with rate constant, initial intensity, and any significant baseline offset as fitting parameters. Time / ms Figure 10: Decay portion of the A-time profile © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 25: The Basics Of Photochemistry
Since the life times of the intermediates are often very short (ms, µs, ns, and less) and their reactions are fast, it is necessary for the methods to be capable of high time resolution. The experiments with the Vernier Flash Photolysis Spectrometer are designed to demonstrate the use of time-resolved techniques in a straightforward and cost-effective way. -
Page 26: Flash Photolysis Experiments
The absorption spectrum of a solution of CR in its trans-ground state (as depicted in Figure 13) in 20% water/ethanol is shown in Figure 12. The dye absorbs strongly throughout the visible range with a maximum near 510 nm. Note that the absorbance is very weak at 600 nm. © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 27: Figure 12: Ground State Absorption Spectrum Of Congo Red (Trans Conf.) In 20% Water In Ethanol
Moreover, the rate is found to be catalyzed by both acids and bases, and the student is required to find the bimolecular rate constant for catalysis by OH ions. © Ultrafast Systems LLC /Vernier Software & Technology... - Page 28 Vernier Flash Photolysis Spectrometer. A useful check is to transfer some of the solution to the 10 mm x 10 mm cuvette and place it in the sample position with the 600 nm band pass filter inserted in front of the detector.
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Page 29: Figure 13: Kinetic Profile Of Congo Red In 20% Water In Ethanol
]. You should find that the decays follow an exponential rate law with a constant that is a linear function of [OH ] and the slope of the line (or the best fit of the regression) is the bimolecular rate constant for the catalytic process. © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 30: Figure 14: Absorption Kinetic Profile Of Congo Red In 20% Water In Ethanol With 2 Mm Oh - Ions
Figure 14: Absorption kinetic profile of Congo red in 20% water in ethanol with 2 mM OH ions © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 31: Isomerization Of Mercury Dithizonate
(Section 5.7). A plot of the observed rate constant as a function of acid concentration is linear with a slope that provides the bimolecular rate constant for the catalysis process. © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 32: Figure 16: Ground State Absorption Spectrum Of Mercury Dithizonate (Trans Conf.) In Ethanol
Photoexcitation of an air-saturated ethanol solution of the Hg complex with the dithizone ligand in the cis-form induces cis-to-trans isomerization, and the compound changes color from orange to blue (λ = 605 nm). © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 33: Figure 17: Trifluoroacetic Acid (Tfa); Mw = 114.03
Figure 17: Trifluoroacetic acid (TFA); MW = 114.03 Figure 18: Kinetic profile of mercury dithizonate in ethanol © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 34: Determination Of The Activation Energy Of The Thermal Back Reaction Of One Spiropyran In Toluene
600 nm of the MC isomer as a function of time. In Reference: Piard, Jonathan, “Influence of the Solvent on the Thermal Back Reaction of One Spiropyran” Journal of Chemical Education. 2014, 91, 2105–2111. © Ultrafast Systems LLC /Vernier Software & Technology... - Page 35 Using Logger Pro, a line is fit through the five data points and the slope of this line is used to calculate the activation energy, E , of the back reaction. © Ultrafast Systems LLC /Vernier Software & Technology...
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Page 36: Figure 20: Ground State Absorption Spectrum Of One Spiropyran In Toluene
Figure 20: Ground state absorption spectrum of one spiropyran in toluene Figure 21: Transient absorption at 600 nm of spiropyran in toluene © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 37: Figure 22: Example Decay And Exponential Fit For 55°C Measurement
Figure 22: Example decay and exponential fit for 55°C measurement Figure 23: Actual data example of ln(τ) as a function of 1000/T. © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 38: Appendix
Appendix Spectra of Flash Lamp and White Light LED Wavelength / nm Figure 24: Emission spectrum of xenon flash lamp © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 39: Figure 25: Emission Spectrum Of White Light Led
Wavelength / nm Figure 25: Emission spectrum of white light LED © Ultrafast Systems LLC /Vernier Software & Technology... -
Page 40: Spectra Of Optical Filters
Spectra of Optical Filters wavelength / nm Figure 26: Transmission spectrum of 600 nm bandpass filter © Ultrafast Systems LLC /Vernier Software & Technology...
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