IP determination and 1+1 REMPI spectrum of SiO at 210–220 nm in an ion trap: Implications for SiO⁺ ion trap loading

The 1+1 REMPI spectrum of SiO in the 210–220 nm range was recorded. Observed bands were mostly assigned to the vibrational bands v^″=0-3,v^′=5-10 of the A-X electronic transition. Additionally, a band near 216–217 nm was tentatively assigned as a 2-photon transition from X to the n=12,13 [X²Σ⁺,v⁺=1] Rydberg states. Based on observed lines we estimated the IP of SiO to be 11.594(5) eV. The SiO⁺ cation has previously been identified as having a cycling transition useful for state control by optical pumping. Our work allowed us to identify an efficient method for loading an ion trap with rotationally and vibrationally cold SiO⁺ from an ablated sample of SiO by photoionizing through the (5,0) A-X band at 213.977 nm.