Ihsan Farouki, a PhD student in Mechanical Engineering, has created a remarkable tool for the spectroscopy community: MCSpectra (www.mcspectra.com), an open-source web-based application that – for the first time – quantifies uncertainty in simulated absorbance and emission spectra.

In spectroscopy, absorbance and emission spectra explain how molecules interact with light—either by absorbing or emitting photons. Spectra simulations are essential in fields ranging from climate science to space exploration, as they help researchers interpret what gases are present in the atmosphere, and identify the temperature and composition of stars far from Earth.

But here's the catch: no simulation is perfect. Every model uses input parameters—such as temperature, pressure, and molecular properties—that carry some degree of uncertainty. Until now, standard spectral tools offered no way to see how those uncertainties ripple through to the final result. That’s a serious blind spot for researchers who rely on this data to validate experiments or calibrate sensors.

“We have frequently faced the need to quantify the uncertainty in simulated spectra which are utilized as reference data for analytical techniques and for evaluating the performance of newly developed experimental methods,” Ihsan explains. “MCSpectra addresses this need for the first time in the domain of spectral simulation tools.”

To overcome the mathematical complexity of this problem—caused by convoluted line shapes and nonlinear propagation of errors—MCSpectra uses Monte Carlo random sampling, generating thousands of possible outcomes to assess how uncertainties impact the final spectrum.

This innovation, developed under the supervision of Prof. Bassam Dally (Mechanical Engineering Program) and Prof. Aamir Farooq (Mechanical Engineering Program)—both faculty in KAUST’s Physical Science and Engineering Division (PSE)—is already gaining recognition.

“Quantifying uncertainty in spectral simulations is critical for applications such as laser-based sensing, remote emissions monitoring, satellite imaging, and astronomical observations,” notes Prof. Farooq. “MCSpectra offers a user-friendly online platform to perform spectral simulations with built-in uncertainty analysis.”

The methodology behind MCSpectra is described in a recent article published in the Journal of Quantitative Spectroscopy and Radiative Transfer (DOI: 10.1016/j.jqsrt.2025.109500). The paper presents example results generated with the tool and outlines some of the features not available in other spectral simulation platforms.

MCSpectra is free to use and open to the wider research community. Prof. Dally adds, “The MCSpectra online site will be highly valuable for users worldwide and is likely to become a standard feature of any publication that uses the available databases.”

Looking ahead, Ihsan plans to expand MCSpectra with new features tailored to the evolving needs of spectroscopists—ensuring the tool remains both innovative and indispensable.