Ionization energies and spatial volumes of the singly occupied molecular orbital in hydrated magnesium clusters [Mg,nH2O]+

Reinhard, Björn M.; Niedner‐Schatteburg, Gereon

doi:10.1063/1.1531108

Cited by 50 publications

(58 citation statements)

References 93 publications

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“…For Mg(H 2 O) 32 2ϩ , we find an average internal energy deposition (E avg ) of about 4.5 eV and a maximum value of 4.8 -5.2 eV. These measured values are slightly higher than the recombination energies calculated at the MP2 level, but are comparable to BLYP values for large n [69].…”

Section: Evidence For Nonergodic Dissociationmentioning

confidence: 45%

“…If internal energy in excess of 7.1 eV was deposited into this ion, MgOH ϩ should have been formed; this ion is not observed. In contrast, the ionization energy of Mg(H 2 O) 5 ϩ is calculated to be 7.92 eV [69]. Ionization energies obtained from CC2 and BLYP calculations for this ion are 7.94 and 8.34 eV, respectively [69], indicating that this result does not depend strongly on the type of theory used.…”

Section: Evidence For Nonergodic Dissociationmentioning

confidence: 85%

“…In contrast, the ionization energy of Mg(H 2 O) 5 ϩ is calculated to be 7.92 eV [69]. Ionization energies obtained from CC2 and BLYP calculations for this ion are 7.94 and 8.34 eV, respectively [69], indicating that this result does not depend strongly on the type of theory used. The lower value obtained from this experiment suggests that less energy is deposited into Mg(H 2 O) 5 2ϩ than would be expected if the entire recombination energy that is potentially available in the EC process were converted to internal modes of the ion.…”

Section: Evidence For Nonergodic Dissociationmentioning

confidence: 85%

“…Thus, the recombination energy values we obtain should be comparable to the adiabatic ionization energies calculated by NiednerSchatteburg and coworkers if all the energy is randomized. The calculated values rapidly decrease with increasing cluster size approaching an asymptotic limit of 3.9 -4.8 and 5.1-5.5 eV for clusters with n ϭ 11-19 at the MP2 and BLYP levels of theory, respectively [69]. For Mg(H 2 O) 32 2ϩ , we find an average internal energy deposition (E avg ) of about 4.5 eV and a maximum value of 4.8 -5.2 eV.…”

Section: Evidence For Nonergodic Dissociationmentioning

confidence: 92%

“…Each of these pieces of evidence is discussed in more detail below. The adiabatic ionization energies of hydrated clusters of Mg(H 2 O) n ϩ have been calculated by Niedner-l Schatteburg and coworkers [69]. Results of these calculations as a function of cluster size are plotted in Figure 8 along with values for the internal energy deposition from EC for selected Mg(H 2 O) n 2ϩ clusters measured here.…”

Section: Evidence For Nonergodic Dissociationmentioning

confidence: 99%

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Nonergodicity in electron capture dissociation investigated using hydrated ion nanocalorimetry

Leib

Donald

Bush

et al. 2007

J. Am. Soc. Mass Spectrom.

118

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Hydrated divalent magnesium and calcium clusters are used as nanocalorimeters to measure the internal energy deposited into size-selected clusters upon capture of a thermally generated electron. The infrared radiation emitted from the cell and vacuum chamber surfaces as well as from the heated cathode results in some activation of these clusters, but this activation is minimal. No measurable excitation due to inelastic collisions occurs with the low-energy electrons used under these conditions. Two different dissociation pathways are observed for the divalent clusters that capture an electron: loss of water molecules (Pathway I) and loss of an H atom and water molecules (Pathway II). For Ca(H 2 O) n 2ϩ , Pathway I occurs exclusively for n Ն 30 whereas Pathway II occurs exclusively for n Յ 22 with a sharp transition in the branching ratio for these two processes that occurs for n Ϸ 24. The number of water molecules lost by both pathways increases with increasing cluster size reaching a broad maximum between n ϭ 23 and 32, and then decreases for larger clusters. From the number of water molecules that are lost from the reduced cluster, the average and maximum possible internal energy is determined to be ϳ4.4 and 5.2 eV, respectively, for Ca(. This value is approximately the same as the calculated ionization energies of M(H 2 O) n ϩ , M ϭ Mg and Ca, for large n indicating that the vast majority of the recombination energy is partitioned into internal modes of the ion and that the dissociation of these ions is statistical. For smaller clusters, estimates of the dissociation energies for the loss of H and of water molecules are obtained from theory. For Mg(H 2 O) n 2ϩ , n ϭ 4 -6, the average internal energy deposition is estimated to be 4.2-4.6 eV. The maximum possible energy deposited into the n ϭ 5 cluster is Ͻ7.1 eV, which is significantly less than the calculated recombination energy for this cluster. There does not appear to be a significant trend in the internal energy deposition with cluster size whereas the recombination energy is calculated to increase significantly for clusters with fewer than 10 water molecules. These, and other results, indicate that the dissociation of these smaller clusters is nonergodic. . The effectiveness of the bottom-up method for complex samples can be enhanced by using multidimensional separations. Clemmer and coworkers elegantly demonstrated that combining on-line liquid chromatography (LC) with ion mobility spectrometry and MS can greatly improve separations without increasing analysis times over LC/MS alone [2][3][4]. In contrast, the "top-down" approach to protein characterization has the advantage that de novo sequencing, including the identification and structural localization of labile posttranslational modifications, can be done directly on protein mixtures without proteolysis [5,6]. This top-down approach has greatly benefited from the development of electron capture dissociation (ECD), a method pioneered by McLafferty and coworkers [6][7][8][9]. In a typical ECD experim...

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Section: Evidence For Nonergodic Dissociationmentioning

confidence: 45%

Section: Evidence For Nonergodic Dissociationmentioning

confidence: 85%

Section: Evidence For Nonergodic Dissociationmentioning

confidence: 85%

Section: Evidence For Nonergodic Dissociationmentioning

confidence: 92%

Section: Evidence For Nonergodic Dissociationmentioning

confidence: 99%

See 3 more Smart Citations

Nonergodicity in electron capture dissociation investigated using hydrated ion nanocalorimetry

Leib

Donald

Bush

et al. 2007

J. Am. Soc. Mass Spectrom.

118

View full text Add to dashboard Cite

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3,4,5‐Trimethoxy Substitution on an N‐DMBI Dopant with New N‐Type Polymers: Polymer‐Dopant Matching for Improved Conductivity‐Seebeck Coefficient Relationship

et al. 2021

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Achieving high electrical conductivity and thermoelectric power factor simultaneously for n-type organic thermoelectrics is still challenging. By constructing two new acceptor-acceptor n-type conjugated polymers with different backbones and introducing the 3,4,5-trimethoxyphenyl group to form the new n-type dopant 1,(TP-DMBI), high electrical conductivity of 11 S cm À1 and power factor of 32 mW m À1 K À2 are achieved. Calculations using Density Functional Theory show that TP-DMBI presents a higher singly occupied molecular orbital (SOMO) energy level of À1.94 eV than that of the common dopant 4-(1, 3dimethyl-2, 3-dihydro-1H-benzoimidazol-2-yl) phenyl) dimethylamine (N-DMBI) (À2.36 eV), which can result in a larger offset between the SOMO of dopant and lowest unoccupied molecular orbital (LUMO) of n-type polymers, though that effect may not be dominant in the present work. The doped polymer films exhibit higher Seebeck coefficient and power factor than films using N-DMBI at the same doping levels or similar electrical conductivity levels. Moreover, TP-DMBI doped polymer films offer much higher electron mobility of up to 0.53 cm 2 V À1 s À1 than films with N-DMBI doping, demonstrating the potential of TP-DMBI, and 3,4,5-trialkoxy DMBIs more broadly, for high performance n-type organic thermoelectrics.

show abstract

3,4,5‐Trimethoxy Substitution on an N‐DMBI Dopant with New N‐Type Polymers: Polymer‐Dopant Matching for Improved Conductivity‐Seebeck Coefficient Relationship

et al. 2021

View full text Add to dashboard Cite

Achieving high electrical conductivity and thermoelectric power factor simultaneously for n‐type organic thermoelectrics is still challenging. By constructing two new acceptor‐acceptor n‐type conjugated polymers with different backbones and introducing the 3,4,5‐trimethoxyphenyl group to form the new n‐type dopant 1,3‐dimethyl‐2‐(3,4,5‐trimethoxyphenyl)‐2,3‐dihydro‐1H‐benzo[d]imidazole (TP‐DMBI), high electrical conductivity of 11 S cm−1 and power factor of 32 μW m−1 K−2 are achieved. Calculations using Density Functional Theory show that TP‐DMBI presents a higher singly occupied molecular orbital (SOMO) energy level of −1.94 eV than that of the common dopant 4‐(1, 3‐dimethyl‐2, 3‐dihydro‐1H‐benzoimidazol‐2‐yl) phenyl) dimethylamine (N‐DMBI) (−2.36 eV), which can result in a larger offset between the SOMO of dopant and lowest unoccupied molecular orbital (LUMO) of n‐type polymers, though that effect may not be dominant in the present work. The doped polymer films exhibit higher Seebeck coefficient and power factor than films using N‐DMBI at the same doping levels or similar electrical conductivity levels. Moreover, TP‐DMBI doped polymer films offer much higher electron mobility of up to 0.53 cm2 V−1 s−1 than films with N‐DMBI doping, demonstrating the potential of TP‐DMBI, and 3,4,5‐trialkoxy DMBIs more broadly, for high performance n‐type organic thermoelectrics.

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Ionization energies and spatial volumes of the singly occupied molecular orbital in hydrated magnesium clusters [Mg,nH2O]+

Abstract: Articles you may be interested inDyson orbitals of N2O: Electron momentum spectroscopy and symmetry adapted cluster-configuration interaction calculations Assessment of the performance of common density functional methods for describing the interaction energies of ( H 2 O ) 6 clusters

Cited by 50 publications

References 93 publications

Nonergodicity in electron capture dissociation investigated using hydrated ion nanocalorimetry

Nonergodicity in electron capture dissociation investigated using hydrated ion nanocalorimetry

3,4,5‐Trimethoxy Substitution on an N‐DMBI Dopant with New N‐Type Polymers: Polymer‐Dopant Matching for Improved Conductivity‐Seebeck Coefficient Relationship

3,4,5‐Trimethoxy Substitution on an N‐DMBI Dopant with New N‐Type Polymers: Polymer‐Dopant Matching for Improved Conductivity‐Seebeck Coefficient Relationship

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