Separate Spectroscopic Detection of Carbenium and Fluoronium Isomers of Protonated Fluorobenzene

Infrared spectra of protonated polycyclic aromatic hydrocarbon molecules: Azulene

“…In fact, such highlying isomers have unambiguously been detected for related protonated aromatic molecules by IRPD spectroscopy of ions generated in an electron impact cluster ion source, such as phenol, 19 para-fluorophenol, 26 and fluorobenzene. 20 For this reason, the IRMPD spectrum is compared to the IR spectra calculated for all six available AzuH + isomers in Fig. 4.…”

“…13 The first technique employs modern, relatively low-intensity, optical parametric oscillator laser systems in the frequency range 800-4000 cm −1 to drive one-photon IRPD of AH + -L n cluster ions. 12 This approach is based on the evaporation of one or more of the weakly bound ligands upon resonant absorption of a single photon ͑messenger technique͒, 14 and has been applied to a variety of AH + -L n cluster ions, including A = benzene, [15][16][17][18] phenol, 12,19 fluorobenzene, 20 para-halogenated phenols, 21 toluene, 17 pyridine, 18 aniline, 22 imidazole, 23 various amino acids and peptides, 24 and neurotransmitters. 25 The IRPD method can also be applied to break weak chemical bonds in certain AH + isomers, 11,26 but usually fails to dissociate common AH + ions because the energy of a single IR photon is insufficient to break strong covalent bonds.…”

Diastereo-specific conformational properties of neutral, protonated and radical cation forms of (1R,2S)-cis- and (1R,2R)-trans-amino-indanol by gas phase spectroscopy

“…For this purpose, the octopole is filled with N 2 up to 10 À5 mbar, resulting in collisions with B10 eV collision energy in the laboratory frame. Recent applications of this IRPD approach of tagged ions in the Berlin laboratory include hydrocarbon ions, [48][49][50][51][52][53][54][55][56][57] silicon-containing ions, [58][59][60] and biological molecules and their hydrates. [61][62][63][64][65][66] 2.3.2.…”

Infrared photodissociation spectroscopy of protonated neurotransmitters in the gas phase

“…Several ways of overcoming the number density restriction have now been developed, each based upon the coupling of ionisation techniques such as electro-spray (ESI), or matrix assisted laser desorption (MALDI), [17][18][19][20][21][22][23][24][25], or electron impact, [26][27][28][29][30][31][32][33] or electrical discharge [34][35][36][37][38] with mass filtering, and cumulative storage in ion traps to enhance their number densities. Their molecular structures have been probed through resonant single, or multiphoton infrared photodissociation spectroscopy.…”

“…Their molecular structures have been probed through resonant single, or multiphoton infrared photodissociation spectroscopy. In general, single photon absorption is sufficient for dissociation of weakly bound complexes (typically, with 'reporter' partners such as Ar, N 2 or H 2 O) [26][27][28][29][30][31][32][33][34][35][36][37][38] but resonantly enhanced multi-photon absorption is required to fragment the bare, uncomplexed ions or proton bound complexes [17,21,22]. Comparisons with high-level quantum chemical calculations facilitate spectral assignments to specific structures and the sensitivity of their near infrared bands, in particular those associated with OH and NH stretching modes, to local hydrogen bonded environments, identifies specific inter-and intramolecular interactions.…”