Input

This is the typical snapshot of the input of ComplexRI.

The input of Complex contains two parts. The first part is the information of ATR-IR experimental data. The second part is the control parameters of the complex refractive index fitting procedure. Each part will be explained in the following.

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Information of ATR-IR experiment

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②ATR-IR File

Please upload the ATR-IR experimental data in this part. The inside should be like the following.

There are two rules for the format of input file.

(1). The format of input file must be txt.

(2). The columns are separated by the space.

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③The order of data

Please select the sort order of your data.

Ascending order: The frequencies in the input file are in ascending order (left picture). (Default)

Descending order: The frequencies in the input file are in descending order (right picture).

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④Reflectance or Absorptance?

Please select the type of your ATR-IR data.

Reflectance(%): The Reflectance of ATR-IR spectra in the value of percentage. (Default)

Reflectance: The Reflectance of ATR-IR spectra.

Absorptance: The Absorptance of ATR-IR spectra.

The relationships between each data are

$Reflectance(\%)=Reflectance*100$

$Absorptance=-\log _{10}(Reflectance)$

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⑦Select the Substrate

Please select the substrate you used in the ATR-IR experiment. Here, we prepare the three substrates often used

Diamond(Refractive Index = 2.38)

Zinc selenide(Refractive Index = 2.40)

Germanium(Refractive Index = 4.0).

You can also input the refractive index of your substrate by selecting Others in the list.

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⑧Incident angle in ATR-IR

Please input the incident angle in your ATR-IR experiment. (Default=45 degree)

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⑤Select the column of your data

Please input the column number of the data you want to analyze in your ATR-IR file.

Wavenumber: The column number of wavenumber in your input file. (Default: 1)

ATR-IR data: The column number of ATR-IR data in your input file. (Default: 2)

For example, an input file like following can be uploaded and column 1 and column 5 can be selected for analyzing.

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Control parameters of ComplexRI fitting

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①Title of your job

Please input the title of your job (alphabet). The output results of ComplexRI will be saved in the excel format with the name @Title.xlsx

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⑥Input the fitting range

Please input the frequency range (in wavenumber) you want to perform the fitting. ComplexRI will fit the data only inside the range you input here.

minimum wavenumber: The lower boundary of wavenumber. (Default: 1636)

maximum wavenumber: The upper boundary of wavenumber. (Default: 1863)

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⑨Refractive index of target sample in non-resnance region ($n_{j}^{0}$)

Please input the refractive index of the target sample ($n_{j}^{0}$) in non-resnance region. (Default=1.360)

$n_{j}^{0}$ should be determined before the fitting procedure (see Equation in ⑪). In the reference paper, we use the refractive index values in the visible regions to fit Cauchy's equation.

$n=A+{\frac {B}{{\lambda }^{2}}}+{\frac {C}{{\lambda }^{4}}}$

The obtained parameters $A,B,C$ were used to evaluate the refractive index at 5000 wavenumber.

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⑩The tolerance of fitting

Please input the tolerance of fitting procedure. The fitting will be finished when the calculated residual is less than this value.

The details are written in the explanation01 of Internal processing.

Notice!! Fitting can not finish if this value is too small.

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⑪ Manually set the initial parameters

Please select whether to set the initial fitting parameters by yourself.

No: Automatically done by the algorithm (Default)

Yes: Manually set the initial parameters by users.

In the fitting, we use a set of Lorentz functions to represent the complex refractive index

$n_{j}=n_{j}^{0}+\sum _{l=1}^{lmax}{\frac {A}{\nu _{l}-\nu -i\gamma }}$

where $n_{j}^{0}$ is input in ⑨. The number of Lorentz functions $lmax$, and the corresponding parameters $A_{l},\nu _{l},\gamma _{l}$ should be determined.

By selecting $No$, it means the initial parameters are automatically guessed by the algorithm explained in the explanation01 of Internal processing .

By selecting $Yes$, you can manually set $lmax$ and $A_{l},\nu _{l},\gamma _{l}$ for each Lorentz function by yourself. $lmax$ is up to 5.