1. Molecular spectroscopy and reaction dynamics Group III
Sigtryggur Bjarki Sigtryggsson
Styrmir Svavarsson
Úlfar Þór Björnsson Árdal

2. Resonance Enhanced Multiphoton Ionization-Time of Flight (REMPI-TOF)

3. History
The phenominon of two photon adsorption was first reported by Maria Geoppert-Mayer in 1931
First used in 1978 by two research groups:
Boels in Germany
Antonov in Russia
Has since been of great importance for the scientific community and resulted in many breakthroughs in molecular spectroscopy

4. Theory
REMPI-TOF uses a high intensity laser to excite molecules (usually small molecules) and atoms.
Because of the high intensity of the laser the molecule/atom can absorb more than one photon wich equal a energy difference between two distinct energy levels.
The virtual state is a very short lived and non-observable state
For each photon absorbed the change in electronic angular momentum can be either 0 or ±1.
If there are more then one photon absorbed the change in electronic angular momentum can be more than ±1.

5. In the (2+1)REMPI-TOF there are two photons used to excite the molecule/atom and one photon used to ionize the particle.
After the ionization the particle is accelerated in an electric field and travels to a detector over a fixed distance. The time from ionization to detection is the time of flight (TOF) of the particle.

6. The equipment

7. Graph 1

8. Graph 2

9. Excited States Ground States Configuration Term J Level (cm-1) 4s24p5
3/2
1/2
3685
Excited States
Configuration
Term J
Level (cm-1) 
4s24p4(3P1)5p 
2D°
5/2
78511
3/2
78676
4D° 
1/2
78860
4s24p4(3P2)5p 
75695
 4P°
75815

10. A+ + e
B+ + e E AB
AB+
+ e
AB**
A + B+
AB # #
A+ + B
A + B/B*
1xhn
2xhn

11. HCl/DCl

12. A typical day at the office