The Granada-Amsterdam Light Scattering Database: Experimental optical properties of cosmic dust analogue samples.

The characterization of dust particles in the Solar System is a fundamental component of planetary science. These particles are present in a variety of environments, including the atmospheres of planets and satellites, comets, or covering the surfaces of planets, moons, and asteroids. The ever-growing number of new exoplanetary systems show that the Solar System is just a particular case in our galaxy. Through the scattering and absorption of stellar radiation, dust particles significantly influence the radiative balance of the corresponding atmosphere. However, their net radiative effect remains one of the major sources of uncertainty in atmospheric modeling. This uncertainty largely stems from a lack of understanding of how stellar radiation is scattered by a cloud of realistic dust particles i.e.  the lack of accurate scattering properties for dust and cloud particles. While modeling these properties is straightforward for homogeneous spheres, it becomes highly complex when dealing with irregularly shaped dust particles.  Hence, the importance of laboratory astrophysics and in particular the characterization of cosmic dust optical properties for proper interpretation of astronomical observations.

Over the last years, the IAA Cosmic Dust Laboratory (IAA-CODULAB) (Muñoz et al., 2011) has generated a substantial collection of high-quality experimental scattering matrices for clouds of randomly oriented cosmic dust analogues. Measurements are conducted at three wavelengths (448 nm, 520 nm, and 640 nm), spanning a wide scattering angle range from 3° to 177°. These datasets are available in digital format through the Granada-Amsterdam Light Scattering Database (scattering.iaa.es) (Muñoz et al., 2025). The database includes the full set of measured scattering matrices along with comprehensive metadata describing the scattering samples, and guidance on how to interpret and utilize the data effectively. The samples presented in the database comprise a wide range of sizes (sub-micron up to mm-sized grains), shapes and compositions. We have recently added the diffuse reflectance spectra of some of our powder samples and, from these spectra, obtained the corresponding refractive indices (200 nm–2000 nm) (Martikainen et al 2023).  In this presentation, we will provide an overview of the database and illustrate its application through examples demonstrating how the experimental data can be used to interpret astronomical observations.

REFERENCES

• Muñoz, O.; Moreno, F.; Guirado, D.; Ramos, J. L. ; Volten, H. ; Hovenier, J. W. The IAA cosmic dust laboratory: Experimental scattering matrices of clay particles. Icarus, Volume 211, Issue 1, p. 894-900, 2011.
• Muñoz, O. Frattin, E.; Martikainen, J. ; Guirado, D. ; Passas-Varo, M. ; Escobar-Cerezo, J. ; García-Izquierdo, F. J. ; Gómez-Martín, J. C. ; Gray, Z. ; Jardiel, T. ; Moreno, F. ; Ocaña, A. J. ; Peiteado, M. ; Gallego-Calvente, A. T. ; Volten, H. Update Granada–Amsterdam Light Scattering Database. JQSRT, 331, id.109252, 2025
• Martikainen, J.; Muñoz, O.; Jardiel, T.; Gómez Martín, JC; Peiteado, M; Willame,Y; Penttilä, A; Muinonen, K.; Wurm, G.; Becker, T. Optical Constants of Martian Dust Analogs at UV-Visible-Near-infrared Wavelengths. ApJ Suppl. Series, 268 (2), id.47, 2003