For advanced users

  1. How can I modify a database?

  2. How can we calculate the lifetime of fluorescence(S1) AND phosphorescence(T1)?

  3. I have a customized database. How do I install the March 6, 2009 update to Version 2.1?

I have a customized database. How do I install the March 6, 2009 update to Version 2.1?

If you have your own customized database, please do not run the PhotochemCAD™ Installer (filename: photochemcad_installer.exe) from the Downloads page. If you run the new installer you could lose your customized database.

To avoid any loss of your own database, please follow these steps:

  1. From the Downloads page, download the zipped PhotochemCAD™ program files (filename: photochemcad.zip). Do not download the PhotochemCAD™ Installer (filename: photochemcad_installer.exe).
  2. Extract the photochemcad.zip file.
  3. Look in the extracted files and locate the folder named Molecule Database. In that folder, locate these two files:
    • MOLECULE_db.db
    • benzene.ems.txt
  4. Replace your existing files named MOLECULE_db.db and benzene.ems.txt with the new files of the same name.

In this manner, your own database will not be affected, and you do not need to install the March 6, 2009 update to PhotochemCAD™ Version 2.1.[top of page]

How can I modify a database?

At present, we do not have a wizard to modify the database.  You need to change the data or files manually.

  1. If you want to change data such as quantum yield, epsilon, solvent etc., please do as follows:

    (i) You should "List Data" from the "Database list and structure" window.  (By left clicking on the compound name in the "Database list and structure" window, you have four options: "Absorption", "Emission", "Light Source", and "List Data".)

    (ii) You will see the "Data Information and Editor" window.  Then you can change any data such as "Name", "Class", "Instrument", etc. as needed.  When you have finished changing the data, please click "save record".  (Do not click "OK" because in doing so the changes you made will not be saved in your database.)

    (iii) If you input an incorrect spectra file when you input database by the "Wizard", you can change the file in the same manner by going to "List Data".  For example, if you select a wrong file name when you input the spectra file (e.g., you choose "xyz.abs.txt", although you intended to choose "abc.abs.txt"), you can change the file name to the correct one in "Database list and structure window.  Then click "OK".

  2. If you want to swap a spectral file (absorption, emission, or light source file), please do as follows:

    (i) Your database file (***.db) and spectra files (***.abs.txt, or ***.ems.txt) should be in the same directory.

    (ii) Please prepare the spectra file and save it as exactly the same file name that you want to replace.  Then, you can simply replace the spectra file that you want to swap.

  3. Suppose you want to delete an entire entry from your database, for example, you have 20 entries (compounds) in your database and you want to delete 10 of them.  You need to directly modify your database file (***.db, *** corresponding to the file name which you saved as a database.  This is a somewhat tedious procedure.  The following is a careful description of the procedure.

    (i) Please go to the designated directory and find your database file that you created when you made your own database.  Normally, you would have saved the file in the following directory; Program file/PhotochemCAD/

    (ii) The file has extension ***.db  (If you cannot find the file, please turn on the extension.  In Windows, you can show the extension of the files by going to Start/Settings/Control Panel/Folder Options/ and you can show the extension of the files.)

    (iii) Please open ***.db file with “notepad” or “wordpad” (Both software programs are available in any Windows computer under Start/Program File/Accessories.)  Although you can open with "MS Word," you need to save as text data (***.txt), then you need to change the extension back to ***.db.  It is recommended that you open the file with “notepad” or “wordpad”.

    (iv) When you open the file, you will see following:

[Spectra]

Number = 20

[1 Absorption]

Name=Naphthalene

Class=polycyclic aromatic hydrocarbon

Instrument=Cary 3

Solvent=cyclohexane

Epsilon=6000

Wavelength=275

Reference=276 nm, e=6000, cyclohexane (Berlman, 1971)

Date=06-09-1995

File=naphthalene.abs.txt

Inv=RAF

Structure=naphthalene.str.bmp

[1 Emission]

Instrument=Spex FluoroMax

Solvent=cyclohexane

QuantumYield=0.23

Reference=0.23, cyclohexane (Berlman, 1971)

Date=06-09-1995

File=naphthalene.ems.txt

Inv=RAF

Provided=Ruchun A. Fuh

Notes=

[1 LightSource]

File =

Cloud =

Date =

Instrument =

Inv =

Location =

Ref =

Time =

[2 Absorption]

Name=Coumarin 314

Class=coumarin

Instrument=Cary 3

Solvent=ethanol

Epsilon=46800

Wavelength=436

Reference=436 nm, e=46800, ethanol (Reynolds, 1975)

Date=06-12-1995

File=coumarin314.abs.txt

Inv=RAF

Structure=coumarin314.str.bmp

[2 Emission]

Instrument=Spex FluoroMax

Solvent=ethanol

QuantumYield=0.68

Reference=0.68, ethanol (Reynolds, 1975)

Date=06-12-1995

File=coumarin314.ems.txt

Inv=RAF

Provided=Ruchun A. Fuh

Notes=Other fluorescence quantum yields (ethanol) include 0.77 (Birge, 1987) and 0.86 (van Gompel, 1989).  The fluorescence yield is only weakly dependent on solvent (van Gompel, 1989).

[2 LightSource]

File =

Cloud =

Date =

Instrument =

Inv =

Location =

Ref =

Time =

[3 Absorption]

Name=p-Terphenyl

Class=oligophenylene

Instrument=Cary 3

Solvent=cyclohexane

Epsilon=33800

Wavelength=276.25

Reference=276 nm, e=33800, cyclohexane (Berlman, 1971)

Date=06-13-1995

File=p-terphenyl.abs.txt

Inv=RAF

Structure=p-terphenyl.str.bmp

[3 Emission]

Instrument=Spex FluoroMax

Solvent=cyclohexane

QuantumYield=0.93

Reference=0.93, cyclohexane (Berlman, 1971)

Date=06-13-1995

File=p-terphenyl.ems.txt

Inv=RAF

Provided=Ruchun A. Fuh

Notes=For further spectroscopic studies of this general class of compounds, see Pavlopoulos (1974).

[3 LightSource]

File =

Cloud =

Date =

Instrument =

Inv =

Location =

Ref =

Time =

. . . . . . . . to be continued…

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Please delete the entire compound data that you want.

If you want to delete the 2nd entry (in this case p-Terphenyl), please delete the following part.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

[2 Absorption]

Name=Coumarin 314

Class=coumarin

Instrument=Cary 3

Solvent=ethanol

Epsilon=46800

Wavelength=436

Reference=436 nm, e=46800, ethanol (Reynolds, 1975)

Date=06-12-1995

File=coumarin314.abs.txt

Inv=RAF

Structure=coumarin314.str.bmp

[2 Emission]

Instrument=Spex FluoroMax

Solvent=ethanol

QuantumYield=0.68

Reference=0.68, ethanol (Reynolds, 1975)

Date=06-12-1995

File=coumarin314.ems.txt

Inv=RAF

Provided=Ruchun A. Fuh

Notes=Other fluorescence quantum yields (ethanol) include 0.77 (Birge, 1987) and 0.86 (van Gompel, 1989).  The fluorescence yield is only weakly dependent on solvent (van Gompel, 1989).

[2 LightSource]

File =

Cloud =

Date =

Instrument =

Inv =

Location =

Ref =

Time =

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

You can delete as many data entries as you want.

Then please go back to the first line.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

 [Spectra]

Number = 20

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

 [Spectra] Number = XXX shows the number of entries in your database.

You need one minus the number of data entries.

For example, if you delete one entry, you need 20 – 1 = 19; enter 19 for the number.

If you delete 10 data entries, off course you need to change 20 to 10.

Next you need to check the sequence of the number for each data entry.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

[Spectra]

Number = 164

[1 Absorption]

Name=Naphthalene

Class=polycyclic aromatic hydrocarbon

Instrument=Cary 3

Solvent=cyclohexane

Epsilon=6000

Wavelength=275

Reference=276 nm, e=6000, cyclohexane (Berlman, 1971)

Date=06-09-1995

File=naphthalene.abs.txt

Inv=RAF

Structure=naphthalene.str.bmp

[1 Emission]

Instrument=Spex FluoroMax

Solvent=cyclohexane

QuantumYield=0.23

Reference=0.23, cyclohexane (Berlman, 1971)

Date=06-09-1995

File=naphthalene.ems.txt

Inv=RAF

Provided=Ruchun A. Fuh

Notes=

[1 LightSource]

File =

Cloud =

Date =

Instrument =

Inv =

Location =

Ref =

Time =

[3 Absorption]

Name=p-Terphenyl

Class=oligophenylene

Instrument=Cary 3

Solvent=cyclohexane

Epsilon=33800

Wavelength=276.25

Reference=276 nm, e=33800, cyclohexane (Berlman, 1971)

Date=06-13-1995

File=p-terphenyl.abs.txt

Inv=RAF

Structure=p-terphenyl.str.bmp

[3 Emission]

Instrument=Spex FluoroMax

Solvent=cyclohexane

QuantumYield=0.93

Reference=0.93, cyclohexane (Berlman, 1971)

Date=06-13-1995

File=p-terphenyl.ems.txt

Inv=RAF

Provided=Ruchun A. Fuh

Notes=For further spectroscopic studies of this general class of compounds, see Pavlopoulos (1974).

[3 LightSource]

File =

Cloud =

Date =

Instrument =

Inv =

Location =

Ref =

Time =

…………………………to be continued…

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Now you can see

Since you deleted the entry for spectra 2, you need to change the following part.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

[3 Absorption]

.....................

.....................

[3 Emission]

.....................

.....................

[3 LightSource]

.....................

.....................

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Please change as follows.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

[2 Absorption]

.....................

.....................

[2 Emission]

.....................

.....................

[2 LightSource]

.....................

.....................

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

[top of page]

How can we calculate the lifetime of fluorescence(S1) AND phosphorescence(T1)?

Lifetimes are a consequence of competitive processes and in general are not easily calculated.  The minimum one can do is to calculate the radiative rate (from the singlet state) on the basis of Einstein's expression, as modified by Strickler and Berg. To estimate the fluorescence lifetime, one would need to know the rates of competing processes (e.g., internal conversion, intersystem crossing).[top of page]

This page was last updated January 25, 2017