The efc is a software platform used to process three-dimensional fluorescence spectrum data (excitation-emission-matrix, EEM) by Prof. Wei He and groups of Prof. Fuliu Xu. The software can process absorption spectrum (abs.) as well because abs. is typically employed when correcting the EEM. The efc includes five functions: (1) data-conversion from the measured EEM or water Raman spectrum by instrument to required dataset which is needed in the subsequent analysis; (2) data-correction by considering inner filter effect, blank subtraction, and quinoline sulfate calibration; (3) component-cognition of EEM by PARAFAC analysis; (4) model-comparison with other PARAFAC models through quantifying their similarity and fitting the EEMs with previous PARAFAC models; and (5) indicator-calculation from EEM and abs. spectra and score-calculation of PARAFAC components.

The software is developed using MATLAB GUI base on the correction procedure of EEM, calculation of fluorescence indicators, and parallel factor (PARAFAC) theory. It is a very friendly toolbox for researchers who are not familiar with PARAFAC analysis with MATLAB. The application scope of this software is not limited to the study of EEM of natural organic matter. We can expand their application in EEM of other substances. Considering that the softwares five important functions: conversion, correction, cognition, comparison, and calculation of EEMs mentioned above, we name this as EEMs' five c, shortly efc.

The main four functions of efc software are shown in Figure 1, including EEM conversion module, EEM correction module, pre-analysis of EEM and abs. module, and EEM-PARAFAC module. The former two modules are used to pretreat the data, the latter two modules are used to calculate the indicators and to conduct parallel factor (PARAFAC) analysis.



Figure 1 The main functions of the efc software