Subject confinement resonances

Modes of operation In Figure 2, Qo is an rf-only quadrupole in which the ion beam is focused colli-sionally to enhance the transmission of ions from Qo to Qi, an rf/dc quadrupole mass filter. Precursor ions are mass selected in Qi and transmitted to Qc where they are confined and subjected to resonant dissociation the product ions are ejected axially and mass-selectively. In an MS/MS experiment, where... 

Cyclotron resonance analyser (also known as Penning ion trap) an instrument that confines ions by placing them in a static magnetic field. Inside the field, the ions are subject to the Lorentzian force that causes ions of a particular m/z to cycle at a specific frequency (cyclotron frequency). 

One subject that attracted much attention is the nonlinear optical properties of these semiconductor nanoclusters [17], The primary objective is to find materials with exceptional nonlinear optical response for possible applications such as optical switching and frequency conversion elements. When semiconductors such as GaAs are confined in two dimensions as ultrathin films (commonly referred to as multiple quantum well structures), their optical nonlinearities are enhanced and novel prototype devices can be built [18], The enhancement is attributed mostly to the presence of a sharp exciton absorption band at room temperature due to the quantum confinement effect. Naturally, this raises the expectation on three-dimensionally confined semiconductor nanoclusters. The nonlinearity of interest here is the resonant nonlinearity, which means that light is absorbed by the sample and the magnitude of the nonlinearity is determined by the excited state... 

Under appropriate conditions, the faradaic current may be used to form images of the electrochemical reactivity of a surface. This is known as scanning electrochemical microscopy (SECM), where the transport and heterogeneous redox activity of species within the junction mediate the tip-substrate interaction. This subject has been thoroughly reviewed [43,44], and an excellent paper demonstrating the transition from STM to SECM is available [45]. The possible contribution of confined redox species to resonant tunneling has also been examined [19,46,47]. 

---