Far-infrared (FIR) and mid-infrared (MIR) fine-structure lines (FSLs) are widely used for studying galaxies nearby and faraway. However, interpreting these lines is complicated by factors including sample and data bias, mismatch between resolved calibrations and unresolved observations, limitations in generalizing from case studies, and unresolved issues like the origin of C II emission and the so-called ``deficit.''In this series of papers, we assemble and analyze the most comprehensive atlas of FSL data to date. We explore their empirical correlations (paper I), compare them with photoionization models that cover multiphase gas (paper II), and discuss their physical origins and the new perspectives they offer for studying physical properties (paper III). The first paper introduces value-added catalogs of global FSL data of low- and high-z galaxies compiled from the literature, covering most of the existing observations, supplemented with ancillary ultraviolet to FIR information. Our analysis focus on commonly used diagnostics, such as electron density, radiation field strength, metallicity, and electron temperature. We present their distributions across different galaxy samples and redshifts, and cross-validate the reliability of these diagnostics in measuring physical conditions. By examining empirical relations, we identify the contribution of active galactic nuclei (AGN) to the FIR FSLs O III88 and O I63, and reveal a bias in density measurements. FIR FSLs show good concordance with their optical counterparts. Our findings indicate that variations in FSL ratios are primarily driven by the relative abundances of emitting ions, underscoring their value as tracers of metallicity and radiation field strength. Finally, we compare the FIR FSL properties of low- and high-z galaxies, discussing both their similarities and differences.
Peng et al. (Mon,) studied this question.