Table 2. Molecular Weights Associated With Calibrated Oxidation Products and Sesquiterpenes Detected by PTR-MS			
Compound	m/z (mass + 1)	Structure	Description
primary signal	21	H218OH+	isotope of primary ion
	37	H2OH2OH+	primary ion water cluster
oxidation products common to all photooxidation experiments	31	CH2OH+	formaldehyde
	45	C2H4OH+	acetaldehyde
	47	CH2O2H+	formic acid
	59	C3H6OH+	acetone
	61	C2H4O2H+	acetic acid
beta-caryophyllene	67, 68, 81a, 82, 95, 109, 121, 137, 149, 205, 206	C15H24H+	sesquiterpene, fragments, and isotopes
	85, 113 c *, 141, 147, 153, 165, 167, 175, 177, 179, 181, 183, 189, 191, 197, 201, 207, 209, 217, 219, 223, 235, 237, 253 b, 		unidentified oxidation products
alpha-humulene	67,  81, 82, 95, 96, 97, 103, 109, 110, 121, 123, 135, 137, 149, 150, 205, 206	C15H24H+	sesquiterpene, fragments, and isotopes
	57, 71, 73, 75, 83, 85, 87, 89, 99, 101, 115, 125, 127, 129, 133, 139, 141, 151*, 153, 155*, 157, 159*, 161, 169*, 175, 179, 183, 191, 193, 209, 219, 223 		unidentified oxidation products
longifolene	81, 82, 95, 96, 103, 109, 110, 121, 123, 124, 135, 136, 149, 150, 205, 206, 207	C15H24H+	sesquiterpene, fragments, and isotopes
	71, 73, 75, 85, 87, 89, 99, 101, 113*, 115, 129, 201, 203, 207, 219, 220d, 221, 223, 235		unidentified oxidation products
aromadendrene	95, 96, 103, 109, 110, 121, 123, 124, 135, 136, 149, 150, 163, 205, 206, 207	C15H24H+	sesquiterpene, fragments, and isotopes
	73, 75, 82, 85, 87, 89, 99, 101, 103, 127, 139, 163, 165, 189, 190d, 191, 203, 207, 209, 219, 221, 222d, 223		unidentified oxidation products
aIons associated with parent terpenes listed in bold font represent ions > 20% of the unfragmented parent terpene.			
bUnidentified oxidation products in bold font are ions with > 5% yield (on a mole basis) from the parent terpene.  			
cUnidentified oxidation products with asterisks represent ions that were observed at Blodgett Forest using PTR-MS [Holzinger et al., 2005]. 			
dEven mass-to-charge ratio oxidation products that are not carbon isotopes of other oxidation products are likely gas-phase nitrogen containing products, e.g., organic nitrates.