1. Introduction  
2. The Odin observations  
2.1. Interesting species  
2.2. Observational strategy  
2.3. Deep searches at 543 GHz during 2007 & 2009  
3. Results  
3.1. Comments on results from the 2004 observations  
3.3. Comments on results of the deep searches  
4. Analysis  
4.1. Linear phase  
4.2. Turn-around phase  
4.3. Non-linear collapse phase  
5. Sensitivity analysis  
5.1. Resonant lines  
5.2. Thermal absorption lines  
6. Summary