Database import
First the required optical constants have to be loaded from the database. Start the program and go to the list of optical constants by pressing the button 'Dielectric functions' in the main window. Now use the Database command to open the database window:
In order to work with a material from the database, you have to transfer it to the list of optical constants. Select the wanted database item (like 'Water (IR)' in the picture above), and then start a drag&drop operation from the button labeled Drag in the upper right corner. Move the mouse cursor into the list of dielectric functions and drop the optical constants here.
We need three materials for our computations: A metal for the sample cup, glass and water for the coated spheres. Please try to find the entries 'Ag model', 'Glass (microscope slide), IR' and 'Water (IR)' in the database and move them to the list of optical constants which should look like this:
Spectral range
Before we can use these materials for SPRAY computations we have to make sure that their spectral range is defined properly. The final diffuse reflectance spectra will be computed in the range 500 ... 5000 1/cm. The range of the individual objects should cover this range (or be larger). Select the 'Ag model' entry and open its window with Edit. Since this is a model, we can compute required data in any spectral range. Use the Range command and select 500 ... 5000 1/cm with 451 data points (i.e. a 10 1/cm resolution). If you want to see the computed optical constants you can press the 'a' on the keyboard for automatic scaling. Eventually you have to change the graphics parameters a little bit in order to see the data like this (see the graphics course for details):
The data for glass and water are fixed imported data sets. Their spectral range cannot be changed. SPRAY will use linear interpolation to compute required values from the given data points.
Interfaces
Now we can define the three interfaces we will need in the following: One for the sample cup walls, one for the uncoated air-glass transition and one for a wet glass surface, i.e. air-water-glass.
In the main window of SPRAY, click the Interface button to open the list of interfaces. Create three objects of type 'Layer stack' and name them like shown below:
Select (like indicated above) the first layer stack and open its window with Edit:
Select the bottom halfspace and press the '+' button to create a thin film in between the two halfspaces. Select the cell named 'Material' of the thin film and press the F4 function key to cycle through all possible choices for optical constants. Stop at 'Ag model'. Type in a new thickness of 1000 nm which will be thick enough to make this metal completely opaque in the infrared. The stack should now look like this:
Close this window and try to define the other two interfaces in a similar way. Here are the final stacks that you should try to reproduce:
I hope you could follow this far. Otherwise you can load with File|Open the current configuration which I have saved under the name tu1_ex2_1.s99.