Identification of atmospheric molecular clusters and measurement of their concentrations by atmos... more Identification of atmospheric molecular clusters and measurement of their concentrations by atmospheric pressure interface time-of-flight (APi-TOF) mass spectrometers may be affected by systematic error due to possible decomposition of clusters inside the instrument. Here, we perform numerical simulations of decomposition in an APi-TOF mass spectrometers and formation in the atmosphere of a set of clusters which involve a representative kind of highly oxygenated organic molecule (HOM), with the molecular formula C 10 H 16 O 8. This elemental composition corresponds to one of the most common mass peaks observed in experiments on ozone-initiated autoxidation of α-pinene. Our results show that decomposition is highly unlikely for the considered clusters, provided their bonding energy is large enough to allow formation in the atmosphere in the first place.
<div&a... more <div>Recent technological developments have made it possible to detect the elemental composition of even the smallest airborne clusters at low ambient concentrations through chemical ionization atmospheric pressure interface time-of-flight mass spectrometry (CI-APi-TOF-MS). The charging process and collisions inside the instrument will however affect the molecular composition of the original sample clusters. A process model is therefore needed to connect the mass spectra to the original molecular clusters in the measured sample.</div><div> </div><div>Our research has been focused on developing this process model for clusters involving highly oxygenated organic molecules (HOM) with molecular formula C<sub>10</sub>H<sub>16</sub>O<sub>8</sub>. This elemental composition corresponds to one of the most common mass peaks observed in experiments on ozone-initiated autoxidation of α-pinene.</div><div> </div><div>For the model, two situations inside the mass spectrometer have to be taken into account: the chemical ionization and collisions with carrier gas inside the atmospheric pressure interface. Recently, a model predicting the fragmentation of clusters as a result of collisions in APi has been developed by Zapadinsky et al. (2018). We used this model to perform numerical simulations of fragmentation in the APi on our selected clusters. The results show that fragmentation is highly unlikely for the considered clusters, provided their bonding energy is large enough to allow formation in the atmosphere in the first place.</div><div> </div><div>Current research is focused on developing a model for the charging process inside CI-APi-TOF MS. Configurational sampling is combined with high quality quantum chemistry calculations to derive the binding energies and evaporation rates of the studied clusters. This model should eventually connect the ionized clusters after charging to the original distribution of neutral clusters in the measured sample.</div>
We measured the fragmentation of clusters inside an MS and we developed a model to describe and p... more We measured the fragmentation of clusters inside an MS and we developed a model to describe and predict their fragmentation.
Proceedings of the National Academy of Sciences of the United States of America, Jan 3, 2018
The quantum motion of nuclei, generally ignored in the physics of sliding friction, can affect in... more The quantum motion of nuclei, generally ignored in the physics of sliding friction, can affect in an important manner the frictional dissipation of a light particle forced to slide in an optical lattice. The density matrix-calculated evolution of the quantum version of the basic Prandtl-Tomlinson model, describing the dragging by an external force of a point particle in a periodic potential, shows that purely classical friction predictions can be very wrong. The strongest quantum effect occurs not for weak but for strong periodic potentials, where barriers are high but energy levels in each well are discrete, and resonant Rabi or Landau-Zener tunneling to states in the nearest well can preempt classical stick-slip with nonnegligible efficiency, depending on the forcing speed. The resulting permeation of otherwise unsurmountable barriers is predicted to cause quantum lubricity, a phenomenon which we expect should be observable in the recently implemented sliding cold ion experiments.
We show clear evidence of a quadratic speedup of a quantum annealing (QA) Schrödinger dynamics ov... more We show clear evidence of a quadratic speedup of a quantum annealing (QA) Schrödinger dynamics over a Glauber master equation simulated annealing (SA) for a random Ising model in one dimension, via an equalfooting exact deterministic dynamics of the Jordan-Wigner fermionized problems. This is remarkable, in view of the arguments of H. G. Katzgraber et al. [Phys. Rev. X 4, 021008 (2014)], since SA does not encounter any phase transition, while QA does. We also find a second remarkable result: that a "quantum-inspired" imaginary-time Schrödinger QA provides a further exponential speedup, i.e., an asymptotic residual error decreasing as a power law τ −μ of the annealing time τ .
Identification of atmospheric molecular clusters and measurement of their concentrations by APi-T... more Identification of atmospheric molecular clusters and measurement of their concentrations by APi-TOF mass spectrometers may be affected by systematic error due to possible decomposition of clusters inside the instrument. Here, we perform numerical simulations of decomposition in an APi-TOF and formation in the atmosphere of a set of clusters which involve a representative kind of highly-oxygenated organic molecule (HOM), with molecular formula C 10 H 16 O 8. This elemental composition corresponds to one of the most common mass peaks observed in experiments on ozone-initiated autoxidation of α-pinene. Our results show that decomposition is highly unlikely for the considered clusters, provided their bonding energy is large enough to allow formation in the atmosphere in the first place. 1 Introduction Recent developments in mass spectrometry have brought huge advancements to the field of atmospheric science. For example, mass spectrometers are now able to detect ppq-level concentrations of both clusters and precursor vapours in atmospheric samples (Junninen et al., 2010; Jokinen et al., 2012), as well as directly explore the chemistry of new-particle formation (NPF)
Identification of atmospheric molecular clusters and measurement of their concentrations by atmos... more Identification of atmospheric molecular clusters and measurement of their concentrations by atmospheric pressure interface time-of-flight (APi-TOF) mass spectrometers may be affected by systematic error due to possible decomposition of clusters inside the instrument. Here, we perform numerical simulations of decomposition in an APi-TOF mass spectrometers and formation in the atmosphere of a set of clusters which involve a representative kind of highly oxygenated organic molecule (HOM), with the molecular formula C 10 H 16 O 8. This elemental composition corresponds to one of the most common mass peaks observed in experiments on ozone-initiated autoxidation of α-pinene. Our results show that decomposition is highly unlikely for the considered clusters, provided their bonding energy is large enough to allow formation in the atmosphere in the first place.
<div&a... more <div>Recent technological developments have made it possible to detect the elemental composition of even the smallest airborne clusters at low ambient concentrations through chemical ionization atmospheric pressure interface time-of-flight mass spectrometry (CI-APi-TOF-MS). The charging process and collisions inside the instrument will however affect the molecular composition of the original sample clusters. A process model is therefore needed to connect the mass spectra to the original molecular clusters in the measured sample.</div><div> </div><div>Our research has been focused on developing this process model for clusters involving highly oxygenated organic molecules (HOM) with molecular formula C<sub>10</sub>H<sub>16</sub>O<sub>8</sub>. This elemental composition corresponds to one of the most common mass peaks observed in experiments on ozone-initiated autoxidation of α-pinene.</div><div> </div><div>For the model, two situations inside the mass spectrometer have to be taken into account: the chemical ionization and collisions with carrier gas inside the atmospheric pressure interface. Recently, a model predicting the fragmentation of clusters as a result of collisions in APi has been developed by Zapadinsky et al. (2018). We used this model to perform numerical simulations of fragmentation in the APi on our selected clusters. The results show that fragmentation is highly unlikely for the considered clusters, provided their bonding energy is large enough to allow formation in the atmosphere in the first place.</div><div> </div><div>Current research is focused on developing a model for the charging process inside CI-APi-TOF MS. Configurational sampling is combined with high quality quantum chemistry calculations to derive the binding energies and evaporation rates of the studied clusters. This model should eventually connect the ionized clusters after charging to the original distribution of neutral clusters in the measured sample.</div>
We measured the fragmentation of clusters inside an MS and we developed a model to describe and p... more We measured the fragmentation of clusters inside an MS and we developed a model to describe and predict their fragmentation.
Proceedings of the National Academy of Sciences of the United States of America, Jan 3, 2018
The quantum motion of nuclei, generally ignored in the physics of sliding friction, can affect in... more The quantum motion of nuclei, generally ignored in the physics of sliding friction, can affect in an important manner the frictional dissipation of a light particle forced to slide in an optical lattice. The density matrix-calculated evolution of the quantum version of the basic Prandtl-Tomlinson model, describing the dragging by an external force of a point particle in a periodic potential, shows that purely classical friction predictions can be very wrong. The strongest quantum effect occurs not for weak but for strong periodic potentials, where barriers are high but energy levels in each well are discrete, and resonant Rabi or Landau-Zener tunneling to states in the nearest well can preempt classical stick-slip with nonnegligible efficiency, depending on the forcing speed. The resulting permeation of otherwise unsurmountable barriers is predicted to cause quantum lubricity, a phenomenon which we expect should be observable in the recently implemented sliding cold ion experiments.
We show clear evidence of a quadratic speedup of a quantum annealing (QA) Schrödinger dynamics ov... more We show clear evidence of a quadratic speedup of a quantum annealing (QA) Schrödinger dynamics over a Glauber master equation simulated annealing (SA) for a random Ising model in one dimension, via an equalfooting exact deterministic dynamics of the Jordan-Wigner fermionized problems. This is remarkable, in view of the arguments of H. G. Katzgraber et al. [Phys. Rev. X 4, 021008 (2014)], since SA does not encounter any phase transition, while QA does. We also find a second remarkable result: that a "quantum-inspired" imaginary-time Schrödinger QA provides a further exponential speedup, i.e., an asymptotic residual error decreasing as a power law τ −μ of the annealing time τ .
Identification of atmospheric molecular clusters and measurement of their concentrations by APi-T... more Identification of atmospheric molecular clusters and measurement of their concentrations by APi-TOF mass spectrometers may be affected by systematic error due to possible decomposition of clusters inside the instrument. Here, we perform numerical simulations of decomposition in an APi-TOF and formation in the atmosphere of a set of clusters which involve a representative kind of highly-oxygenated organic molecule (HOM), with molecular formula C 10 H 16 O 8. This elemental composition corresponds to one of the most common mass peaks observed in experiments on ozone-initiated autoxidation of α-pinene. Our results show that decomposition is highly unlikely for the considered clusters, provided their bonding energy is large enough to allow formation in the atmosphere in the first place. 1 Introduction Recent developments in mass spectrometry have brought huge advancements to the field of atmospheric science. For example, mass spectrometers are now able to detect ppq-level concentrations of both clusters and precursor vapours in atmospheric samples (Junninen et al., 2010; Jokinen et al., 2012), as well as directly explore the chemistry of new-particle formation (NPF)
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Papers by Tommaso Zanca