Ion-pair photodissociations of benzyl chloride through inner-valence electron excitations

Vacuum Ultraviolet Negative Photoion Spectroscopy of Chloroform

“…The IPAES of Cl − and the other negative ion fragments were recorded at the atomic and molecular physics end-station of the national synchrotron radiation facility at Hefei, China. The apparatus has been described in detail elsewhere. ,, Its reliability and sensitivity have been proved by comparison of our IPAES of CO 2 with that available in the literature. , As shown in Figure (upper panel), the vacuum-UV photon beam was monochromatized with the undulator-based spherical gratings (made by Horiba Jobin Yvon) and then focused onto the photoionization region. A diffuse molecular beam was introduced with a stainless steel tube with a diameter of 0.5 mm.…”

“…Positive ion−negative ion pair (simply noted as ion-pair) photodissociation, established as a novel unimolecular process, occurs rather commonly in the wide energy range (from several to hundreds of electronvolts) − and for a variety of molecules. − When ion-pair predissociation states are coupled with the vibrational states of a certain valence excited state or Rydberg state, correspondingly, ion-pair anion efficiency spectra (IPAES) exhibit the discrete structures that can be assigned with Rydberg-like or vibrational-excited series. − On the other hand, in the photoexcitation when the target molecule is vertically promoted to the repulsive wall of the potential energy surfaces of the ion-pair states, the structureless band will be presented in IPAES due to the direct fast ion-pair dissociations. For polyatomic molecules, the multibody fragmentation is also frequently observed above the molecular ionization threshold.…”

“…Thus, it is difficult to access the experimental studies of the ion-pair dissociation, not only due to its minor contribution to the decaying channels of the molecular excited states but also the requirement of an energy-broad light source. It is appealing that such demanding is satisfied well with the high sensitivity of the state-of-art time-of-flight (TOF) mass spectrometry and the broad-band tunability of synchrotron radiation. − ,− …”

Positive and Negative Photoion Spectroscopy Study of Monochlorothiophenes

“…The thermodynamic values in eq are required in the interpretations to the ion-pair anion efficiency spectra (IPAES) of Cl – , − because a lot of dissociation paths may be involved in such wide energy range. Moreover, some electronic and vibrational excitations may couple with the ion-pair dissociations, showing the discrete structures or peaks in the IPAES. − Therefore, the interpretations to the IPAES and the spectral assignments heavily depend on the other spectral sources such as photoabsorption, photoelectron, and photoion mass spectra. However, only photoelectron spectra (PES) of monochlorothiophenes are available; thus, the present PIE spectra of monochlorothiophenes will play an essential role in the interpretations to the IPAES.…”

“…In this work, the chlorine anion Cl – as the product in the ion-pair dissociation of monochlorothiophenes is observed in a wide photon energy range of 10.70–22.00 eV. The thermodynamic values in eq are required in the interpretations to the ion-pair anion efficiency spectra (IPAES) of Cl – , − because a lot of dissociation paths may be involved in such wide energy range. Moreover, some electronic and vibrational excitations may couple with the ion-pair dissociations, showing the discrete structures or peaks in the IPAES. − Therefore, the interpretations to the IPAES and the spectral assignments heavily depend on the other spectral sources such as photoabsorption, photoelectron, and photoion mass spectra.…”