Home >
Community >
How can I convert epsilon to transmission or absorbance in IR...
Upvote
27
Downvote
+ Computational chemistry
+ Ir spectra
+ Gaussian (software)
Posted by
Manuel Aparicio-Conde
How can I convert epsilon to transmission or absorbance in IR...
I might add that in practice the calculated transition intensities are embarked with such a substantial residual error that you may safely forget about comparing their absolute values to the experimental ones. This is the primary source of ambiguity here. Also, how often do you measure vibrational spectra of isolated molecules? Because this is what you get in the calculations. This disregards all the dynamics occurring in real system, e.g. vibrational dephasing. Stick to the relative intensities (that is one calculated peak vs the others) as these may be reasonably accurately resembling the analogous relationships observable in the experimental spectra.
I might add that in practice the calculated transition intensities are embarked with such a substantial residual error that you may safely forget about comparing their absolute values to the experimental ones. This is the primary source of ambiguity here. Also, how often do you measure vibrational spectra of isolated molecules? Because this is what you get in the calculations. This disregards all the dynamics occurring in real system, e.g. vibrational dephasing. Stick to the relative intensities (that is one calculated peak vs the others) as these may be reasonably accurately resembling the analogous relationships observable in the experimental spectra.
Gaussian should be able to give out either the functions of the absorption index, or the absorption coefficients etc. It could not calculate an absorption (absorbance?) spectrum otherwise. I hope someone familiar with Gaussian will help you.
Gaussian should be able to give out either the functions of the absorption index, or the absorption coefficients etc. It could not calculate an absorption (absorbance?) spectrum otherwise. I hope someone familiar with Gaussian will help you.
the UV-vis plot obtained is epsilon vs wavelength plot. I tried using the equation from the gaussian page of UV-Vis spectra, but the value deviates from the value from the plot. Thanks Thomas MayerHofer.
the UV-vis plot obtained is epsilon vs wavelength plot. I tried using the equation from the gaussian page of UV-Vis spectra, but the value deviates from the value from the plot. Thanks Thomas MayerHofer.
its an absorption spectra obtained using gaussian 16, using TD-DFT methods. from the plot I want to obtain the epsilon values of the peaks. is there a way to find it using gaussview. I tried finding in .log file. could not find anywhere.
its an absorption spectra obtained using gaussian 16, using TD-DFT methods. from the plot I want to obtain the epsilon values of the peaks. is there a way to find it using gaussview. I tried finding in .log file. could not find anywhere.
Be aware of the fact, that the Beer-Lambert law actually only describes propagation in but not transmission through a medium. A correct calculation of the latter does require the full dielectric function (tensor).
Be aware of the fact, that the Beer-Lambert law actually only describes propagation in but not transmission through a medium. A correct calculation of the latter does require the full dielectric function (tensor).
GaussView operates with *.out file and visualizes as well 1H, 13C-NMR, Raman, NBO data, MOs and more. It is really a good software for visualization (and not only for visualization) of your theoretical data in publs.
Please find as attchment an example how looks a theoretically predicted IR-spectrum by Gaussian.
GaussView operates with *.out file and visualizes as well 1H, 13C-NMR, Raman, NBO data, MOs and more. It is really a good software for visualization (and not only for visualization) of your theoretical data in publs.
Please find as attchment an example how looks a theoretically predicted IR-spectrum by Gaussian.
Depends. What kind of spectra did you record (transmission or reflection spectra? If reflection, internal, external or diffuse? If transmission, layer or liquid sample? If layer, what kind of substrate, if liquid, what is the thickness of the cuvette etc.). In other words, to help you we would require much more information...
Depends. What kind of spectra did you record (transmission or reflection spectra? If reflection, internal, external or diffuse? If transmission, layer or liquid sample? If layer, what kind of substrate, if liquid, what is the thickness of the cuvette etc.). In other words, to help you we would require much more information...
I might add that in practice the calculated transition intensities are embarked with such a substantial residual error that you may safely forget about comparing their absolute values to the experimental ones. This is the primary source of ambiguity here.
Also, how often do you measure vibrational spectra of isolated molecules? Because this is what you get in the calculations. This disregards all the dynamics occurring in real system, e.g. vibrational dephasing.
Stick to the relative intensities (that is one calculated peak vs the others) as these may be reasonably accurately resembling the analogous relationships observable in the experimental spectra.
I might add that in practice the calculated transition intensities are embarked with such a substantial residual error that you may safely forget about comparing their absolute values to the experimental ones. This is the primary source of ambiguity here.
Also, how often do you measure vibrational spectra of isolated molecules? Because this is what you get in the calculations. This disregards all the dynamics occurring in real system, e.g. vibrational dephasing.
Stick to the relative intensities (that is one calculated peak vs the others) as these may be reasonably accurately resembling the analogous relationships observable in the experimental spectra.
More
VOTE
Gaussian should be able to give out either the functions of the absorption index, or the absorption coefficients etc. It could not calculate an absorption (absorbance?) spectrum otherwise. I hope someone familiar with Gaussian will help you.
Gaussian should be able to give out either the functions of the absorption index, or the absorption coefficients etc. It could not calculate an absorption (absorbance?) spectrum otherwise. I hope someone familiar with Gaussian will help you.
More
VOTE
the UV-vis plot obtained is epsilon vs wavelength plot. I tried using the equation from the gaussian page of UV-Vis spectra, but the value deviates from the value from the plot. Thanks Thomas MayerHofer.
the UV-vis plot obtained is epsilon vs wavelength plot. I tried using the equation from the gaussian page of UV-Vis spectra, but the value deviates from the value from the plot. Thanks Thomas MayerHofer.
More
VOTE
its an absorption spectra obtained using gaussian 16, using TD-DFT methods. from the plot I want to obtain the epsilon values of the peaks. is there a way to find it using gaussview. I tried finding in .log file. could not find anywhere.
its an absorption spectra obtained using gaussian 16, using TD-DFT methods. from the plot I want to obtain the epsilon values of the peaks. is there a way to find it using gaussview. I tried finding in .log file. could not find anywhere.
More
VOTE
Dear Bojidarka B. Ivanova;
Can you take the procedure how can I do this in GaussView;
Best Regards
Dear Bojidarka B. Ivanova;
Can you take the procedure how can I do this in GaussView;
Best Regards
More
VOTE
Be aware of the fact, that the Beer-Lambert law actually only describes propagation in but not transmission through a medium. A correct calculation of the latter does require the full dielectric function (tensor).
Be aware of the fact, that the Beer-Lambert law actually only describes propagation in but not transmission through a medium. A correct calculation of the latter does require the full dielectric function (tensor).
More
VOTE
How can we get the exact value of epsilon for the peaks in UV spectra?
How can we get the exact value of epsilon for the peaks in UV spectra?
More
VOTE
you can calculate IR spectrum with Gaussian from properties , and you can convert absorbance to transmission by click option convert abs. to tra.
you can calculate IR spectrum with Gaussian from properties , and you can convert absorbance to transmission by click option convert abs. to tra.
More
VOTE
Mr. Kumar,
useful software for this purpose is GaussView.
It may be found in http://www.gaussian.com/g_prod/gv5.htm.
GaussView operates with *.out file and visualizes as well 1H, 13C-NMR, Raman, NBO data, MOs and more. It is really a good software for visualization (and not only for visualization) of your theoretical data in publs.
Please find as attchment an example how looks a theoretically predicted IR-spectrum by Gaussian.
Mr. Kumar,
useful software for this purpose is GaussView.
It may be found in http://www.gaussian.com/g_prod/gv5.htm.
GaussView operates with *.out file and visualizes as well 1H, 13C-NMR, Raman, NBO data, MOs and more. It is really a good software for visualization (and not only for visualization) of your theoretical data in publs.
Please find as attchment an example how looks a theoretically predicted IR-spectrum by Gaussian.
More
VOTE
Depends. What kind of spectra did you record (transmission or reflection spectra? If reflection, internal, external or diffuse? If transmission, layer or liquid sample? If layer, what kind of substrate, if liquid, what is the thickness of the cuvette etc.). In other words, to help you we would require much more information...
Depends. What kind of spectra did you record (transmission or reflection spectra? If reflection, internal, external or diffuse? If transmission, layer or liquid sample? If layer, what kind of substrate, if liquid, what is the thickness of the cuvette etc.). In other words, to help you we would require much more information...
More
VOTE