[Fe II] emission lines are prominent in the infrared (IR) and important as diagnostic tools for radiative atomic shocks. We investigate the emission characteristics of [Fe II] lines using a shock code developed by Raymond (1979) with updated atomic parameters. We rst review general characteristics of the IR [Fe II] emission lines from shocked gas, and derive their uxes as a function of shock speed and ambient density. We have compiled available IR [Fe II] line observations of interstellar shocks and compare them to the ratios predicted from our model. The sample includes both young and old supernova remnants in the Galaxy and the Large Magellanic Cloud and several Herbig-Haro objects. We nd that the observed ratios of the IR [Fe II] lines generally fall on our grid of shock models, but the ratios of some mid- IR lines, e.g., [Fe II] 35.35 m=[Fe II] 25.99 m, [Fe II] 5.340 m=[Fe II] 25.99 m, and [Fe II] 5.340 m=[Fe II] 17.94 m, are signicantly oset from our model grid. We discuss possible explanations and conclude that while uncertainties in the shock modeling and the observations certainly exist, the uncertainty in atomic rates appears to be the major source of discrepancy.

Abstract
1. INTRODUCTION
2. ATOMIC CONSTANTS AND BASIC APPLICATIONS
    2.1. Atomic Constants
    2.2. Basic Applications
3. RADIATIVE ATOMIC SHOCKS ANDIR [FE II] EMISSION
    3.1. Shock Code and Model Parameters
    3.2. Shock Structure and [Fe II] Emission
    3.3. IR [Fe II] Line Fluxes and Comparisonwith Other Shock Models
4. SHOCK GRIDS AND COMPARISON TOOBSERVATIONS
    4.1. NIR [Fe II] Lines
    4.2. MIR [Fe II] Lines
5. DISCUSSION
    5.1. Atomic Physics
    5.2. Shock Models
    5.3. Observational Uncertainties
6. CONCLUSIONS
REFERENCES

• Bon-Chul Koo(Department of Physics and Astronomy, Seoul National University/Visiting Professor, Korea Institute for Advanced Study) Corresponding author
• John C. Raymond(Harvard-Smithsonian Center for Astrophysics)
• Hyun-Jeong Kim(Department of Physics and Astronomy, Seoul National University)