Contribute Datasets

Creating a Data Set for the Optical Constants Database

Creating a data set for the Optical Constants database starts with specifying the spectral data and associated contextual information to insert into the database. We ask that a data set consist of one or more spectral data derived from published work.

A single Optical Constants database record generally contains at least one index of refraction spectrum (either the real part of the complex index of refraction (n), or the imaginary part of the complex index of refraction (k), or both) and can also include one or more other associated spectrum (transmission, reflection, absorption).

For your convenience, we have provided an Excel workbook that organizes the information requirements described below. The Excel workbook contains a page that represents a single data record, and this page can be duplicated for multiple records. One copy of the Excel workbook can therefore be used to store information for all of the data records from a single published work that are being contributed.

The Composition of a Data Set

Here is a summarized list of the information we ask you to provide to contribute a data set to the Optical Constants database (more detailed instructions are provided within the workbook template):

Each data set should include at least one spectrum.

Spectral Data: The actual values of each spectrum can be provided in a separate text file, preferably in a comma-separated values (csv) format. For each spectrum, we need to know the type of spectrum and the relevant data units.

For the moment, the display functionality of the optical constants database web pages works with the following optical properties:

• real (n) part of the complex refractive index (unit: dimensionless number)
• imaginary (k) part of the complex refractive index (unit: dimensionless number)
• transmittance spectra (unit: percent, dimensionless ratio, other)
• reflectance spectra (unit: percent, dimensionless ratio, other)
• absorbance spectra (unit: logarithm base-10 scale, natural logarithm scale, other)

Other types of spectra could be supported in the future.

The units of the spectral property of light used in the provided data set also needs to be provided (A, nm, µm…).

If available, point-wise error values for the measured material property values can also be included. An optional explanatory caption to provide for the spectrum when graphed as a figure can also be provided.

Along with the contributed spectral data files, we ask that the components (ice or gas) used to generate the samples be described.

Ice Components: For “ices” and “ice tholins” data sets, please specify the ice components that were used to produce the sample. These ice components can either be:

• the composition of the ice sample when the measurement was conducted (for “ices” data sets)
• the ice components used to create a precursor material that was subsequently subjected to further processing (for “ice tholins” data sets)

Each ice component should be listed as its common English name and provided with a molecular formula. If available, please provide the fraction of the composition of each ice component. Since there are multiple ways of measuring the fraction of a sample that consists of a given ice component (e.g., fraction of the sample by mass, fraction of the sample by volume, etc.), we ask that a short text description of the methodology for determining this fraction be provided as well.

Gas Components: For “gas tholins” data sets, please specify the gas components that were used to create the sample. Each gas component should be listed as its common English name and provided with a molecular formula. If available, please provide the fraction of a gas mixture that a component represents. As with the ice components, we ask that a short text description of the methodology for determining this fraction be provided as well.

The Optical Constants database only contains data sets that have already been published in peer-reviewed journals. Each data set therefore needs to be linked to a published reference.

References: The full reference information for each cited work should be provided along with a DOI link if available.

To better support future search options that will become available for the database, a data set can include a description of "processes" performed on a sample at a fixed temperature and pressure.

Processes: Examples of processes are provided in a drop down menu in the template excel workbook. They include: deposition of an ice sample onto a cold substrate mounted within a vacuum chamber with the substrate temperature and vacuum pressure fixed, measurement of spectra of a sample at a fixed sample temperature and pressure, or subjecting a sample to ultraviolet light processing at a fixed sample temperature and pressure.

Annotations: Additional contextual information associated with a data set can also be provided.