data preparation for transient absorption spectra fitting

An Introduction to Processing, Fitting, and Interpreting Transient Absorption Data

Data Preparation for Transient Absorption Spectra Fitting

To begin, open the fitting software and load the sample dataset. Click on the Surface menu and select Subtract Scattered Light. In the new window, use the arrow buttons and set the number of background Spectra to Average to 10 for performing background correction.Click on Accept to perform the subtraction. Next, remove the unhelpful portions of the spectrum and focus on the spectrum displayed in the lower left. Click on end wavelengths.Input new values and press enter. Adjust the spectral window to the desired wavelength range. Go to the Surface menu, select Crop, and confirm by clicking OK.To save the changes, click on the File menu, select Save File As, click OK, and then close the dataset.Open the solvent blank dataset and begin the trip correction process by adjusting the spectral display. In the heat map tile on the top left, click the crosshair tool and drag the vertical line to the blue end of the spectrum, starting near the blue wavelength range at the beginning of the spectral window. Then, navigate to the Kinetics menu and select Fit Solvent Response.In the new window titled Fit Solvent Response, click on the Fit button. Perform this at least five different wavelengths spaced out across the entire spectrum. After the last point, click Save and then close the window.Next, open the previously cropped and background subtracted dataset. In the Surface menu, select the Chirp Correction option. Add the recently created Chirp Correction by choosing Add from file, selecting the file ending in FitCoefficients and confirming with OK.Click on the preview Chirp Correction button and observe the correction in the top left window, ensuring that the data appears temporarily flattened without any curvature.If the correction is satisfactory, finalize it by clicking the Apply and Exit button. Navigate to the file menu. Select Save file as.Enter a suitable name to reflect the Chirp Correction application, and then click OK.To locate features in the data that should be removed, navigate to the upper left heat map tile. Use the crosshair within the negative time region to identify the start and end wavelengths of the scattering feature. Begin with the lower or blue wavelength of 654 nanometers in the spectrum lower left tile.Select the right end wavelength and input the value for the lower feature extent. Crop the data by selecting Surface from the menu, choosing crop, and then clicking OK in the popup menu. Save the crop data with a unique file name indicating which side of the data it is, and then close the file.Next, open the previously saved Chirp Correction file, and proceed to the features higher or red wavelength extent. Select the left end wavelength on the spectrum in the lower left tile and input the value for the higher extent of the feature. To crop the data, navigate to the Surface menu, select Crop, and then click OK in the popup menu.Save the crop data with a distinctive file name to indicate the side of the data it represents. Combine the two files by going to File and selecting Combine Multiple Surfaces. Select both sides of the data in the new window using Control Click.Ensure both files are chosen in the file name box, and then click OK to confirm. Click on File and choose Save file as to save the combined file. Assign a unique file name to indicate its combined status, and click OK to save.A corrected heat map and representative spectra data are shown here. The results demonstrate how the data should look after applying the corrections. The data set is now ready for fitting.

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Data Fitting Procedure for Transient Absorption Spectra Processing