arXiv subjects

Pintu Mandal

Publications and source records attributed to Pintu Mandal.

6 recordsLinked to original sources

arXiv2026

Anomalous Peak Formation in the Second Stability Zone of Quadrupole Mass Filters: Role of Non-linear Resonances Induced by Single Rod Defects

Operating a quadrupole mass filter (QMF) within its second stability zone offers superior mass resolving power but introduces extreme sensitivity to structural imperfections. While symmetric misalignments are well-documented, this work combines analytical modeling with SIMION trajectory simulations to investigate the unaddressed electrodynamic impact of a completely localized, asymmetric defect on a single rod. Unlike diagonally symmetric perturbations, which reduce the four-fold rotational symmetry to two-fold symmetry while maintaining a smooth stability landscape, a single-rod defect breaks the remaining symmetry, giving rise to pronounced transmission ridges within the second stability zone. Spatial multipole expansion reveals that this structural breakdown injects odd-parity harmonics -- dominated by the hexapole A3 field -- which couple the orthogonal transverse equations of motion. By tracking secular indices through explicit zone-II Floquet projection mappings, we demonstrate that these asymmetric fields drive destructive, higher-order nonlinear secular resonances. Ions traversing these precise parametric coordinates undergo rapid amplitude growth and collide with adjacent electrodes, establishing critical geometric tolerance frameworks and operating conditions for high-performance mass spectrometry.

physics.chem-ph↗

arXiv2026

Geometrical Imperfections in a Digital Quadrupole Mass Filter: A Comprehensive Simulation Study in the First Stability Zone

Geometrical imperfections in quadrupole mass filters introduce higher-order field components that can significantly influence device performance, particularly under non-sinusoidal excitation. In this work, a comprehensive simulation study is carried out to investigate the effect of geometrical imperfections on the performance of a rectangular wave driven quadrupole mass filter operating in the first stability zone. Radial field distortions arising from controlled variations in rod geometry and position, including single rod radius variation, single rod displacement, diagonal rod radius variation, and diagonal rod displacement, are examined. These imperfections introduce octupole field components that distort the ideal quadrupolar field distribution. The influence of such distortions on key performance parameters, namely mass resolution and ion transmission efficiency, is systematically evaluated. The results show that the presence of radial asymmetry leads to a degradation of both resolution and transmission efficiency in all cases considered. Furthermore, the study reveals a strong dependence of mass filter performance on the initial state of the applied pulsed waveform, specifically whether the asymmetric rod pair is subjected to the high or low level of the RF pulse. These findings provide important insights into the tolerance limits of geometrical imperfections and their impact on the performance of pulsed wave driven quadrupole mass filters, which are relevant for the design and optimization of high-resolution digital mass filtering systems.

physics.chem-ph↗

arXiv2026

Performance of Quadrupole Mass Filter with Tapered and Flared Geometry

The performance of a quadrupole mass filter (QMF) is highly sensitive to deviations from ideal electrode geometry. In this work, we investigate the effect of small inward and outward tilting of cylindrical rods on the resolution and transmission characteristics of a QMF. Such geometric perturbations introduce an axial variation in the radial confinement potential, resulting in Mathieu parameters that vary along the ion trajectory. To examine this effect, the ion stability diagram is computed using a Runge Kutta (RK45) method with axially-varying Mathieu parameters. The modified stability region exhibits shift and contraction depending on the magnitude and nature of rod inclination. The evolution of higher order field components, particularly the dodecapole term, is analyzed along the axial direction. Ion trajectory simulations are performed using SIMION to evaluate the corresponding changes in QMF transmission characteristics in the first stability zone of operation. While simulations at fixed operating conditions indicate a transmission resolution trade off at small tilting angles leading to resolution enhancement, analysis at constant peak transmission reveals that even slight deviations from the parallel configuration lead to a degradation in resolution. These results highlight the critical role of minute geometric imperfections in QMF operation and provide insights into tolerance limits and design optimization for improved mass filter performance.

physics.chem-ph↗

arXiv2026

Influence of octupole field on quadrupole mass filter performance in the second stability zone

Radial asymmetry in a quadrupole mass filter (QMF), introduced by symmetric displacement of a diagonally opposite rod pair, modifies the confinement potential and alters the ion stability characteristics. In this work, the influence of such radial asymmetry on QMF operation in the second stability zone is investigated through simulations. Using an existing potential formulation for a radially asymmetric QMF, the stability diagram in the second stability zone is extracted for the first time, revealing a systematic shift of the stability apex with the asymmetry parameter. Radial asymmetry introduces additional multipole components, notably an octupole term whose magnitude scales with the asymmetry parameter and whose sign depends on the DC polarity applied to the displaced rods. Transmission simulations show that the transmission peak shifts in accordance with the displaced stability apex, while the resolution exhibits a strong dependence on both the asymmetry parameter and the DC polarity. Comparable maximum resolution is obtained for inward and outward displacements under suitable polarity configurations, with outward displacement providing higher transmission efficiency due to an increased effective aperture. These results demonstrate that controlled radial asymmetry provides an effective means to tailor the resolution and transmission characteristics of QMFs operating in the second stability zone.

physics.chem-ph↗

arXiv2025

Radial asymmetry in quadrupole mass filters: stability, multipole fields and resolution enhancement

This study examines the effects of radial asymmetry in a linear quadrupole mass filter with circular rods, introduced either by a change in electrode radii or by displacement of a diametrically opposite pair. A radial potential model is developed to account for the resulting geometric deviations, enabling analysis of the first stability region specific to the quadrupole component. The transmission characteristics of such asymmetric configurations are systematically examined, revealing a linear shift in the transmission peak along the q-axis as a function of the asymmetry parameter. This behavior is interpreted through modifications observed in the stability diagram. Furthermore, increased asymmetry is shown to broaden the transmission contours and generally reduce resolution. Notably, a `magic' asymmetry parameter of -0.02 corresponding to electrode displacement, yields enhanced resolution compared to the symmetric case for a fixed rod-to-field radius ratio. An empirical relationship is established between the resolution and the combined contribution of the coefficients of octupole and dodecapole potential components, highlighting the critical role of higher-order field effects in performance optimization.

physics.chem-ph↗

arXiv2025

Effect of Rod Asymmetry on Field Distortions and Transmission Characteristics in Linear Quadrupole Mass Filters

This article reports the appearance of the octupole and hexadecapole components in the radial potential, which are otherwise absent in a linear quadrupole mass filter of symmetric round-rod configuration, if a small structural asymmetry is introduced in one electrode. Using the commercial ion simulation package SIMION, it is shown that the weightage of the octupole and hexadecapole potential increases with an increase in the asymmetry factor. A consistent correlation is observed between the octupole and dodecapole components, and between the hexadecapole and icosapole components with asymmetry added to different rod-to-field radius ratios. The transmission characteristics of the mass filter are studied for different asymmetry factors and rod-to-field radius ratios. The variation in the resolution parameter, as derived from the transmission contour, exhibits a strong correlation with the combined weightage of the multipole fields.

physics.chem-ph↗