Alexander Haack
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View article: Exploring Field-Induced Fragmentation of Protonated Alcohols: Mechanistic Insights and Stabilizing Ion–Solvent Clusters
Exploring Field-Induced Fragmentation of Protonated Alcohols: Mechanistic Insights and Stabilizing Ion–Solvent Clusters Open
Field-induced ion activation in medium to high pressure regions of a mass spectrometer or ion mobility spectrometer can lead to changes in the ion structure, namely unfolding, tautomerization, or fragmentation. To either prevent mislabelin…
View article: On the Arrival Time Distribution of Reacting Systems in Ion Mobility Spectrometry
On the Arrival Time Distribution of Reacting Systems in Ion Mobility Spectrometry Open
Ion mobility spectrometry (IMS) is a widely used gas-phase separation technique, particularly when coupled with mass spectrometry (MS). Modern IMS instruments often apply elevated reduced field strengths for improved ion separation and ion…
View article: Graphormer-IR: Graph Transformers Predict Experimental IR Spectra Using Highly Specialized Attention
Graphormer-IR: Graph Transformers Predict Experimental IR Spectra Using Highly Specialized Attention Open
Given that Infrared (IR) spectroscopy is a crucial tool in various chemical and forensic domains, improved in silico methods for predicting experimental spectra are needed due to the time and accuracy limitations of ab initio methods. We e…
View article: Graphormer-IR: Graph Transformers Can Predict Experimental IR Spectra Using Highly Specialized Attention
Graphormer-IR: Graph Transformers Can Predict Experimental IR Spectra Using Highly Specialized Attention Open
Infrared (IR) spectroscopy is crucial in various chemical and forensic domains, but faster in silico methods for predicting experimental spectra are needed due to the time and accuracy limitations of ab initio methods. We employ Graphormer…
View article: Predicting Ion-Solvent Clustering in Differential Mobility Spectrometry using Anharmonic Thermochemistry
Predicting Ion-Solvent Clustering in Differential Mobility Spectrometry using Anharmonic Thermochemistry Open
Computed dispersion plot models can provide a window to understanding differential mobility spectrometry on a fundamental level and thus can be used as a complementary model to compare with experimental data obtained in a laboratory settin…
View article: Investigating the Rydberg states and photodissociation dynamics of Kr<sub>2</sub> using velocity map imaging
Investigating the Rydberg states and photodissociation dynamics of Kr<sub>2</sub> using velocity map imaging Open
Although the krypton dimer, Kr 2 , is a prototypical weakly bound van der Waals complex in its ground electronic state, the excited states of Kr 2 exhibit many and various interactions. Resonance-enhanced multiphoton ionization and velocit…
View article: MobCal-MPI 2.0: an accurate and parallelized package for calculating field-dependent collision cross sections and ion mobilities
MobCal-MPI 2.0: an accurate and parallelized package for calculating field-dependent collision cross sections and ion mobilities Open
MobCal-MPI-2.0, the first major update from its predecessor, calculates an ion's CCS and high-field mobility with optimized accuracy and efficiency.
View article: Spectroscopic and Theoretical Study on Siloxy-Based Molybdenum and Tungsten Alkylidyne Catalysts for Alkyne Metathesis
Spectroscopic and Theoretical Study on Siloxy-Based Molybdenum and Tungsten Alkylidyne Catalysts for Alkyne Metathesis Open
A combined spectroscopic and theoretical study on triphenyl- and dimethyl-phenyl siloxy molybdenum and tungsten alkylidyne catalysts for alkyne metathesis is reported. Using NMR, X-ray, UV–vis, and resonance Raman spectroscopy and density …
View article: Productive Alkyne Metathesis with “Canopy Catalysts” Mandates Pseudorotation
Productive Alkyne Metathesis with “Canopy Catalysts” Mandates Pseudorotation Open
Molybdenum alkylidyne complexes of the "canopy catalyst" series define new standards in the field of alkyne metathesis. The tripodal ligand framework lowers the symmetry of the metallacyclobutadiene complex formed by [2 + 2] cycloaddition …
View article: Experimental and theoretical study of the reactivity of a series of epoxides with chlorine atoms at 298 K
Experimental and theoretical study of the reactivity of a series of epoxides with chlorine atoms at 298 K Open
Many aspects of the chemical properties of epoxides have been studied so far. However, the geometrical characteristics of this kind of compound could have some implications on the reactivity trends and elucidation of reaction mechanisms. T…
View article: Computational analysis of the proton‐bound acetonitrile dimer, (ACN) <sub>2</sub> H <sup>+</sup>
Computational analysis of the proton‐bound acetonitrile dimer, (ACN) <sub>2</sub> H <sup>+</sup> Open
Rationale In atmospheric pressure ionization mass spectrometry the theoretical thermodynamic treatment of proton‐bound cluster stabilities helps us to understand the prevailing chemical processes. However, such calculations are rather chal…
View article: Charge Retention/ChargeDepletion in ESI-MS: TheoreticalRationale
Charge Retention/ChargeDepletion in ESI-MS: TheoreticalRationale Open
Gas\nphase modification in ESI-MS can significantly alter the charge\nstate distribution of small peptides and proteins. The preceding paper\npresented a systematic experimental study on this topic using Substance\nP and proposed a charge …
View article: Theoretical Investigations on Cluster Formation in Mass Spectrometry
Theoretical Investigations on Cluster Formation in Mass Spectrometry Open
The thermochemistry and reaction dynamics of polar gas phase molecules clustering around an ion in atmospheric pressure ionization mass spectrometry (API-MS) dominate many observed effects. While the equilibrium conditions under elevated p…