A vector correlation study using a hexapole-oriented molecular beam: photodissociation dynamics of oriented isohaloethane.

The photodissociation dynamics of isohaloethane (1-bromo-2-chloro-1,1,2-trifluoroethane) at 234 nm was studied by a sliced imaging technique combined with an oriented molecular beam. The speed and angular distributions of the competitive products of spin-orbit selected Br and Cl atoms were determined by analysis of the obtained images. The anisotropic parameter, ß, was found to be 2.0 ± 0.2 for the excited state of Br(2P1/2) (Br*) and 1.2 ± 0.3 for the ground state of Br(2P3/2) (Br). The speed distributions for both Br and Br* exhibited Gaussian-like characteristics. These results indicate that Br atoms were generated by direct formation after excitation through the nσ*(C-Br) potential energy surfaces. In contrast, the angular distributions for the Cl fragments were almost isotropic, while the speed distributions displayed Boltzmann-like characteristics. This suggests that the Cl atoms may form through long-lived parent molecules after photoexcitation. The branching ratio for Br and Cl atom formation was found to be approximately 1.2, that is, Br atom formation occurred preferentially, in contrast to the case of halothane photodissociation reported in our previous work [Che et al., J. Phys. Chem. A, 2020, 124, 5288]. A vector correlation study between the laser polarization axis and the direction of the dipole moment revealed a similar tendency for all photofragments, suggesting that the fragments were formed through a common excited state of isohaloethane. The vector correlation was also studied theoretically for comparison with the experimental results. The angle between the transition dipole moment in photodissociation and the permanent dipole moment was found to be 42 ± 15°. The obtained results indicate that this vector correlation approach combined with an oriented molecular beam is a powerful tool for determining the transition dipole moments in photodissociation.

Photodissociation Dynamics of CF2ClCHFI Using Slice Imaging Combined with a Hexapole-Oriented Molecular Beam.

Photodissociation dynamics of 1-chloro-2-iodo-1,1,2-trifluoroethane (CF2ClCHFI) were investigated at 267 nm by a slice imaging technique combined with an oriented molecular beam. The speed and angular distributions of the spin-orbit-selected I atoms were determined by analyzing the images. The anisotropic parameter was 1.67 ± 0.04 for the ground state of I(2P3/2) and 1.94 ± 0.04 for the excited state of I(2P1/2). A vector correlation study between the laser polarization and the dipole moment of the molecule revealed that the transition dipole moment in photoabsorption was found to be at 90° ± 15 to the molecular dipole moment, suggesting the transition dipole moment was nearly parallel to the C-I bond axis. The quantum yield for the excited state obtained from the observed signal intensities was estimated to more than 0.9 at this wavelength. The analysis of the kinetic energy release for both fragments indicated that a large amount of energy was distributed into the internal energy of the CF2ClCHF· radical, which led to the secondary reaction of the C-Cl bond rupture. The study of the ground state of Cl atom formation via photolysis at 235 nm supported the existence of the secondary reaction. The results of the kinetic energy release of the I photofragments and the analysis of the image for the photofragment of the Cl atom suggested that the ground state of I atom formation mainly led to the secondary reaction of the C-Cl bond rupture through the short-lived CF2ClCHF· radical. However, only part of the excited state of I atom formation involved the Cl atom formation through the long-lived CF2ClCHF· radical.

Probing BrCl from photodissociation of CH2BrCl and CHBr2Cl at 248 nm using cavity ring-down spectroscopy.

Photodissociation of di- and tri-halogenated methanes including CH2BrCl and CHBr2Cl at 248 nm was investigated using cavity ringdown absorption spectroscopy (CRDS). The spectra of the BrCl(v'' = 2, 3) and Br2(v'' = 1, 2) fragments were probed over the wavelength range of 594.5-596 nm in the B3Π+0u ← X1Σ+g and B3Π (0+) ← X1Σ+ transitions, respectively. Their corresponding spectra were simulated for assignment of rotational lines at a given vibrational level. The quantum yields for Br2 eliminated from CHBr2Cl and BrCl from CH2BrCl were determined to be 0.048 ± 0.018 and 0.037 ± 0.014, respectively. The photodissociation of CHBr2Cl yielded only the Br2 fragment, but not the BrCl fragment in the experiments. An ab initio theoretical method based on the CCSD(T)//B3LYP/6-311g(d,p) level was employed to evaluate the potential energy surface for the dissociation pathways to produce Br2 and BrCl from CHBr2Cl, which encountered a transition state barrier of 445 and 484 kJ mol-1, respectively. The corresponding RRKM rate constants were calculated to show that the branching ratio of (Br2/BrCl) is ∼20. The BrCl spectrum is expected to be obscured by the much larger Br2 spectrum, explaining why BrCl fragments cannot be detected in the photolysis of CHBr2Cl.

Photodissociation of CH2BrCHBrC(O)Cl at 248 nm: probing Br2 as the primary fragment using cavity ring-down spectroscopy.

The photodissociation of 2,3-dibromopropionyl chloride (CH2BrCHBrC(O)Cl, 2,3-DBPC) at 248 nm was carried out to study Br2 as the primary molecular product in the B3Π+0u ← X1Σ+g transition using cavity ring-down absorption spectroscopy. The rotational spectra (v'' = 0-2) were acquired and assigned with the aid of spectral simulation. It is verified that the obtained Br2 fragment is attributed to the one-photon dissociation of 2,3-DBPC and is free from contributions of secondary reactions. The vibrational ratio of the Br2 population of v(0):v(1):v(2) is equal to 1:(0.58 ± 0.12):(0.23 ± 0.09), corresponding to the Boltzmann vibrational temperature of 623 ± 38 K. The quantum yield of Br2 eliminated from 2,3-DBPC is estimated to be 0.09 ± 0.04. The dissociation pathways of 2,3-DBPC and its potential energy surfaces were calculated using density functional theory. By employing the CCSD(T)//M062X/6-31+g(d,p) level of theory, transition state barriers and corresponding reaction energies were calculated for the Br, Cl, Br2, BrCl, HBr and HCl elimination channels. The unimolecular rate constant for Br2 elimination was determined to be 2.09 × 105 s-1 using Rice-Ramsperger-Kassel-Marcus (RRKM) theory, thus explaining the small quantum yield of the Br2 channel.

Prognostic ability of mid-term worsening renal function after percutaneous coronary intervention: findings from the SHINANO registry.

Chronic kidney disease is a prognostic factor for cardiovascular disease. Worsening renal function (WRF), specifically, is an important predictor of mortality in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention (PCI). We evaluate the prognostic impact of mid-term WRF after PCI on future cardiovascular events. We examined the renal function data of 1086 patients in the first year after PCI using the SHINANO 5-year registry. Patients were divided into two groups, mid-term WRF and non-mid-term WRF, and primary outcomes were major adverse cardiovascular events (MACE) and death. Mid-term WRF was defined as an increase in creatinine (≥ 0.3 mg/dL) in the first year after PCI. Mid-term WRF was found in 101 patients (9.3%), and compared to non-mid-term WRF, it significantly increased the incidence of MACE (p < 0.001), and all-cause death (p < 0.001), myocardial infarction (p = 0.001). Furthermore, mid-term WRF patients had higher incidence of future heart failure (p < 0.001) and new-onset atrial fibrillation (p = 0.01). Patients with both mid-term WRF and chronic kidney disease had increased MACE compared to patients with either condition alone (p < 0.001). Similarly, patients with mid-term WRF and acute kidney injury had increased MACE compared to patients with either condition alone (p < 0.001). Multivariate Cox regression analysis revealed mid-term WRF as a strong predictor of MACE (hazard ratio: 2.50, 95% confidence interval 1.57-3.98, p < 0.001). Mid-term WRF after PCI negatively affects MACE, as well as future admission due to heart failure and new-onset atrial fibrillation, chronic kidney disease, and acute kidney injury.

UV Photodissociation of Halothane in a Focused Molecular Beam: Space-Speed Slice Imaging of Competitive Bond Breaking into Spin-Orbit-Selected Chlorine and Bromine Atoms.

A molecular beam of halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) is focused by a hexapolar electrostatic field and photolyzed by UV laser radiation at 234 nm. Angular and speed distributions of chlorine and bromine photofragments emitted from halothane are measured for both spin-orbit states independently. Although the dissociation energy of the C-Cl bond is larger than that of C-Br, the relative yield of Cl to Br was found to be approximately 2. Measured speed and angular distributions of atomic fragments show distinct kinetic energy release and scattering characteristics: for bromine, observed fast and aligned fragments exhibit a signature of a direct mode of dissociation for the C-Br bond, via the electronically excited potential energy surface denoted nσ*(C-Br), of repulsive nature; for chlorine, a variation in the features is observed for the dissociation pathway through nσ*(C-Cl), from a modality similar to the bromine case, leading to fragments with appreciable kinetic energy release and pronounced directionality, to a modality involving slow products, nearly isotopically distributed. The origin of this behavior can be attributed to nonadiabatic interaction operating between the nσ*(C-Br) and nσ*(C-Cl) surfaces. These results are not only relevant for a detailed understanding of adiabatic versus diabatic coupling mechanisms in the manifold of excited states populated by photon absorption, but they also point out the possibility of selectively inducing specific dissociation pathways, even when involving energetically unfavorable outcomes, such as, in this case, the prevailing rupture of the stronger C-Cl bond against that of the weaker C-Br bond.

Photodissociation of CH2BrI using cavity ring-down spectroscopy: in search of a BrI elimination channel.

Photodissociation of CH2BrI was investigated in search of unimolecular elimination of BrI via a primary channel using cavity ring-down absorption spectroscopy (CRDS) at 248 nm. The BrI spectra were acquired involving the first three ground vibrational levels corresponding to A3Π1 ← X1Σ+ transition. With the aid of spectral simulation, the BrI rotational lines were assigned. The nascent vibrational populations for v'' = 0, 1, and 2 levels are obtained with a population ratio of 1 : (0.58 ± 0.10) : (0.34 ± 0.05), corresponding to a Boltzmann-like vibrational temperature of 713 ± 49 K. The quantum yield of the ground state BrI elimination reaction is determined to be 0.044 ± 0.014. The CCSD(T)//B3LYP/MIDI! method was employed to explore the potential energy surface for the unimolecular elimination of BrI from CH2BrI.

Vectorial imaging of the photodissociation of 2-bromobutane oriented via hexapolar state selection.

Molecular orientation techniques are becoming available in the study of elementary chemical processes, in order to highlight those structural and dynamical properties that would be concealed by random rotational motions. Recently successful orientation was achieved for asymmetric-top and chiral molecules of much larger complexity than hitherto. In this work, we report and discuss the correlation between the vectors' photofragment recoil velocity v, transition dipole moment µ, and permanent dipole moment d in a dissociation experiment on hexapole oriented 2-bromobutane, photoinitiated by a linearly polarized laser. The sliced ion images of the Br*(2P1/2) and Br(2P3/2) photofragments were acquired at 234.0 and 254.1 nm, respectively, by a (2 + 1) resonance-enhanced multiphoton ionization technique. A detailed analysis of the sliced ion images obtained at a tilting angle 45° of laser polarization provides information on the correlation of the three vectors, which are confined by two polar angles α and χ and one azimuthal angle φµd in the recoil frame. The sliced ion images of Br fragments eliminated individually from the enantiomers at 254.1 nm yield an asymmetric factor close to zero; for this reason the photofragment angular distributions do not show significant differences. The elimination of the Br* fragment at 234.0 nm is mainly correlated with a parallel transition, giving rise to a large anisotropy parameter of 1.85, and thus can be considered as a single state excitation. The resulting recoil frame angles are optimized to 163° ± 8° and 164° ± 1° for α and χ, respectively, whereas φµd is approaching 0° for the best fit. Since for the present molecule, the three vectors have an only slight spatial arrangement, the photofragment angular distributions of the two enantiomers do not show appreciable differences. Theoretical and computational simulations provide us the basis to state that oriented enantiomers can be discriminated on-the-fly in photodissociation processes even initiated by non-circularly polarized light, provided that the three vectors encountered above have specific three-dimensional arrangements. The fact that Br fragment elimination involves a multi-potential dissociation carries uncertainties in theoretical estimates of the vector direction. Therefore, this work represents a preliminary but significant step on the road to chiral discrimination on-the-fly, which is shown to be best propitiated in molecules where vectors are far from having degenerate mutual angular directions.

Stereodynamic Imaging of Bromine Atomic Photofragments Eliminated from 1-Bromo-2-methylbutane Oriented via Hexapole State Selector.

Both single-laser and two-laser experiments were conducted to look into the ion-imaging of Br*(2P1/2) and Br(2P3/2) photofragmented from 1-bromo-2-methylbutane in the range 232-240 nm via a detection scheme of (2+1) resonance-enhanced multiphoton ionization. The angular analysis of these photofragment distributions yields the anisotropy parameter ß = 1.88 ± 0.06 for the Br* excited state which arises from a parallel transition, while ß = 0.63 ± 0.09 for the Br ground state indicates the contribution from both a perpendicular transition and a non-adiabatic transition. When a hexapole coupled with an orienting field was implemented, the parent molecules are spatially oriented to yield an orientation efficiency |⟨cos Î¸⟩| of 0.15. Besides the χ angle between the recoil velocity v and the transition dipole moment µ, orienting molecules allows for the evaluation of the angle α between v and the permanent molecular dipole moment d. The angular analysis of Br* photofragment distribution yields χ = 11.5° and α in the range from 160° to 180° with weak dependency. In the two-laser experiments, the angular anisotropy of Br photofragment distribution was found to be smaller (0.38 ± 0.10) when the photolysis wavelength was red-shifted to 240 nm, suggesting the increasing contributions from perpendicular transitions.

Cavity Ring-Down Absorption Spectroscopy: Optical Characterization of ICl Product in Photodissociation of CH2ICl at 248 nm.

Iodine monochloride (ICl) elimination from one-photon dissociation of CH2ICl at 248 nm is monitored by cavity ring-down absorption spectroscopy (CRDS). The spectrum of ICl is acquired in the transition of B3Π0 ← X1Σ+ and is confirmed to result from a primary photodissociation, that is, CH2ICl + hν → CH2 + ICl. The vibrational population ratio is determined with the aid of spectral simulation to be 1:(0.36 ± 0.10):(0.11 ± 0.05) for the vibrational levels ν = 0, 1, and 2 in the ground electronic state, corresponding to a Boltzmann-like vibrational temperature of 535 ± 69 K. The quantum yield of the ICl molecular channel for the reaction is obtained to be 0.052 ± 0.026 using a relative method in which the scheme CH2Br2 → CH2 + Br2 is adopted as the reference reaction. The ICl product contributed by the secondary collisions is minimized such that its quantum yield obtained is not overestimated. With the aid of the CCSD(T)//B3LYP/MIDI! level of theory, the ICl elimination from CH2ICl is evaluated to follow three pathways via either (1) a three-center transition state or (2) two isomerization transition states. However, the three-center concerted mechanism is verified to be unfavorable.

Stereodirectional images of molecules oriented by a variable-voltage hexapolar field: Fragmentation channels of 2-bromobutane electronically excited at two photolysis wavelengths.

The asymmetric-top molecule 2-bromobutane is oriented by means of a hexapole state selector; the angular distribution of the bromine atom photofragment, for the two fine-structure components, is acquired by velocity-map ion imaging. The molecular beam, spatially oriented along the time-of-flight axis, is intersected with a linearly polarized laser, whose polarization is tilted by 45° with respect to the detector surface. To obtain the mixing ratio of the perpendicular and parallel transitions, the fragment ion images and angular distributions can be appropriately simulated to give insight on the population mechanism of the specific electronic state involved at each selected excitation wavelength. The photofragment images obtained at 238.6 nm yielded an asymmetry factor ß1 of 0.67, indicative of the extent of molecular orientation, and an anisotropy parameter ß2 of 1.03, which is a signature of a prevailing parallel transition along the C-Br axis. When the photolysis wavelength is tuned to 254.1 nm, the corresponding angular distribution is less asymmetric (ß1 = 0.24) and the obtained small value ß2 = 0.12 is a characteristic of a predominantly perpendicular transition. The photofragment angular distributions are also affected by hexapole voltage, especially regarding the asymmetry factor, and this aspect provides information on the effect of molecular orientation.

Rovibrationally Excited Molecules on the Verge of a Triple Breakdown: Molecular and Roaming Mechanisms in the Photodecomposition of Methyl Formate.

For the photodissociation of the simplest of esters, methyl formate HCOOCH3, the energy threshold for triple fragmentation into H, CH3O, and CO was measured by previous ion-imaging experiments at a sequence of wavelengths. The translational energy features of product CO in the ground vibrational level (υ = 0) and for selected rotational states were characterized. In this integrated experimental and theoretical approach (i) the focus is at a laser energy barely below that threshold; (ii) Fourier-transform infrared emission spectroscopy measurements probe the rovibrational energy deposition in CO(υ) for υ > 0 and the emergence of the roaming phenomenon; (iii) accompanying quantum chemical calculations describe the selective rupture of bonds; and (iv) molecular dynamics simulations of dissociation are performed, introducing an approach explicitly involving outcomes from paths originated nonadiabatically through conical intersections. Quantitative information on energy disposal is provided: we found extensive vibrational excitation of CO, while rotational bands are colder and bimodal, due to contributions from direct and roaming modes.

Hexapole-Oriented Asymmetric-Top Molecules and Their Stereodirectional Photodissociation Dynamics.

Molecular orientation is a fundamental requisite in the study of stereodirected dynamics of collisional and photoinitiated processes. In this past decade, variable hexapolar electric filters have been developed and employed for the rotational-state selection and the alignment of molecules of increasing complexity, for which the main difficulties are their mass, their low symmetry, and the very dense rotational manifold. In this work, for the first time, a complex molecule such as 2-bromobutane, an asymmetric top containing a heavy atom (the bromine), was successfully oriented by a weak homogeneous field placed downstream from the hexapolar filter. Efficiency of the orientation was characterized experimentally, by combining time-of-flight measurements and a slice-ion-imaging detection technique. The application is described to the photodissociation dynamics of the oriented 2-bromobutane, which was carried out at a laser wavelength of 234 nm, corresponding to the breaking of the C-Br bond. The Br photofragment is produced in both the ground Br ((2)P3/2) and the excited Br ((2)P1/2) electronic states, and both channels are studied by the slice imaging technique, revealing new features in the velocity and angular distributions with respect to previous investigations on nonoriented molecules.

Roaming as the dominant mechanism for molecular products in the photodissociation of large aliphatic aldehydes.

Photodissociation of isobutyraldehyde (C3H7CHO) at 248 nm is investigated using time-resolved Fourier-transform infrared emission spectroscopy to demonstrate the growing importance of the roaming pathway with increasing molecular size of aliphatic aldehydes. Each acquired CO rotational distribution from v = 1 to 4 is well characterized by a single Boltzmann rotational temperature from 637 to 750 K, corresponding to an average rotational energy of 5.9 ± 0.6 kJ mol(-1). The roaming signature that shows a small fraction of CO rotational energy disposal accompanied by a vibrationally hot C3H8 co-fragment is supported by theoretical prediction. The energy difference between the tight transition state (TS) and the roaming saddle point (SP) is found to be -27, 4, 15, 22, and 30 kJ mol(-1) for formaldehyde, acetaldehyde, propionaldehyde, isobutyraldehyde, and 2,2-dimethyl propanal, respectively. The roaming SP is stabilized by a larger alkyl moiety. It is suggested that the roaming photodissociation rate of aldehydes increasingly exceeds those via the tight TS, resulting in the dominance of the CO + alkane products, as the size of aldehydes becomes larger. Along with formaldehyde, acetaldehyde, and propionaldehyde, in this work isobutyraldehyde is further demonstrated that this aldehyde family with special functional group is the first case in the organic compound to follow predominantly a roaming dissociation pathway, as the molecular size becomes larger.

Communication: photodissociation of CH3CHO at 308 nm: observation of H-roaming, CH3-roaming, and transition state pathways together along the ground state surface.

Following photodissociation of acetaldehyde (CH3CHO) at 308 nm, the CO(v = 1-4) fragment is acquired using time-resolved Fourier-transform infrared emission spectroscopy. The CO(v = 1) rotational distribution shows a bimodal feature; the low- and high-J components result from H-roaming around CH3CO core and CH3-roaming around CHO radical, respectively, in consistency with a recent assignment by Kable and co-workers (Lee et al., Chem. Sci. 5, 4633 (2014)). The H-roaming pathway disappears at the CO(v ≥ 2) states, because of insufficient available energy following bond-breaking of H + CH3CO. By analyzing the CH4 emission spectrum, we obtained a bimodal vibrational distribution; the low-energy component is ascribed to the transition state (TS) pathway, consistent with prediction by quasiclassical trajectory calculations, while the high-energy component results from H- and CH3-roamings. A branching fraction of H-roaming/CH3-roaming/TS contribution is evaluated to be (8% ± 3%)/(68% ± 10%)/(25% ± 5%), in which the TS pathway was observed for the first time. The three pathways proceed concomitantly along the electronic ground state surface.

Roads leading to roam. Role of triple fragmentation and of conical intersections in photochemical reactions: experiments and theory on methyl formate.

The exploration of alternative roads that open to molecules with sufficient energy to yield different products permits prediction and eventually control of the outcomes of chemical reactions. Advanced imaging techniques for monitoring laser-induced photodissociation are here combined with dynamical simulations, involving ample sets of classical trajectories generated on a quantum chemical potential energy surface. Methyl formate, HCOOCH3, is photodissociated at energies near the triple fragmentation threshold into H, CO and OCH3. Images of velocity and rotational distributions of CO exhibit signatures of alternative routes, such as those recently designated as transition-state vs. roaming-mediated. Furthermore, a demonstration of the triple fragmentation route is given, and also confirmed by H-atom product imaging and FTIR time-resolved spectra of the intermediate HCO radical. In addition, the relevance of nonadiabatic transitions promoted by a conical intersection is clarified by simulations as the privileged "reactivity funnel" of organic photochemistry, whereby the outcomes of molecular photoexcitation are delivered to electronic ground states.

Control of conformers combining cooling by supersonic expansion of seeded molecular beams with hexapole selection and alignment: experiment and theory on 2-butanol.

Selection and alignment of rotamers and, more in general, of conformers in the gas phase is a challenge that we tackle experimentally by supersonic expansion of seeded molecular beams and hexapolar electrostatic fields with quadrupole mass detection. The studied system involves the nine conformers of the asymmetric-top molecule 2-butanol, which coexist because of nearly free rotations around a CC and a CO bond. From the measured time-of-flight of a 2-butanol supersonic molecular beam seeded in either He or Ar, the corresponding velocity distributions are obtained. The different nature and masses of the seeding gas decrease selectively the vibrational temperature and determine the population of the conformers, which is assessed on the basis of their statistical distribution, derived from high level accompanying quantum mechanical calculations. The use of a hexapolar electrostatic field permits us to induce a variation of the population distribution as a function of the applied voltage and of the selective focusing and alignment of the conformers. A technique, recently developed for treating asymmetric tops and involving extensive trajectory simulations, is applied to obtain the link between the focusing curves, i.e. the dependence of the beam intensity on the hexapole voltage, and the conformers' populations and alignment. Perspectives are provided for photo- and stereo-dynamics experiments, particularly appealing also on account that 2-butanol is the simplest chiral alcohol.

Directions of chemical change: experimental characterization of the stereodynamics of photodissociation and reactive processes.

This perspective article aims at accounting for the versatility of some current experimental investigations for exploring novel paths in chemical reactions. It updates a previous one [Phys. Chem. Chem. Phys., 2005, 5, 291] and is limited to work by the authors. The use of advanced molecular beam techniques together with a combination of modern tools for specific preparation, selection and detection permits us to discover new trends in reactivity in the gas phase as well as at interfaces. We specifically discuss new facets of stereodynamics, namely the effects of molecular orientation and alignment on reactive and photodissociation processes. Further topics involve roaming paths and triple fragmentation in photodissociation probed by imaging techniques, chirality effects in collisions and deviations from Arrhenius behavior in the temperature dependence of chemical reactions.

Quantification of peracetic acid (PAA) in the H2O2 + acetic acid reaction by the wavelength shift analysis in near-UV/visible absorption region.

In our study, we present an innovative method for the analysis and real-time monitoring of peracetic acid (PAA) formation within the near-UV/Vis (visible) wavelength region. PAA's absorption spectrum, influenced by its presence in a complex quaternary equilibrium mixture with hydrogen peroxide (H2O2), acetic acid, and water, lacks discernible peaks. This inherent complexity challenges conventional analytical techniques like Beer's law, which rely on absorption intensity as a foundation. To address this challenge, we introduce a novel approach that centers on the analysis of blue shifts in absorption wavelengths, particularly at an absorbance of 0.8 a.u. This method significantly enhances the precision of calibration curves for both diluted PAA and H2O2, unveiling an exponential correlation between wavelength and the logarithm of concentration for both components. Significantly, our approach allows for real-time and accurate measurements, especially during the dynamic PAA formation reaction. Our results exhibit excellent agreement with data obtained from Fourier-transform infrared (FT-IR) spectroscopy, validating the reliability of our method. It's noteworthy that under stable PAA concentration conditions (after 12 h of solution interaction), both traditional absorption method and our approach closely align with the FT-IR method. However, in dynamic scenarios (0-12 h), the absorption method exhibits higher error rates compared to our approach. Additionally, the increased concentration of a catalyst, sulfuric acid (H2SO4), significantly reduces the errors in both methods, a finding that warrants further exploration. In summary, our study not only advances our understanding of PAA and its spectral behavior but also introduces innovative and precise methods for determining PAA concentration in complex solutions. These advancements hold the potential to revolutionize the field of chemical analysis and spectroscopy.

Impact of Low Bone Mineral Content Index on Cardiovascular Outcomes in Patients With Coronary Artery Disease Undergoing Percutaneous Coronary Intervention.

The prognostic value of bone mineral content (BMC) for the clinical outcomes of patients with coronary artery disease (CAD) remains unknown. The present study evaluated the association between BMC index (BMCI) and cardiovascular events between January 2020 to June 2021, in consecutive patients (n = 257) with CAD undergoing percutaneous coronary intervention (PCI) at the Nagano Municipal Hospital. BMCI was measured using bioelectrical impedance analysis and calculated as the BMC divided by height squared. Patients were classified as low (<0.918) or high BMCI (≥0.918) groups according to the receiver operating characteristics curve analysis for the primary endpoint, major adverse cardiovascular events (MACE), including cardiovascular death, spontaneous myocardial infarction, stroke, and any revascularization. During a median follow-up of 744 days, the low BMCI group (n = 152) had an increased risk of MACE compared with the high group (n = 105) (19.7 vs 6.7%, P = .004). A low BMCI was significantly associated with MACE in the multivariable Cox and the Inverse Probability of Treatment Weighting analyses (hazard ratio: 3.16, 95% confidence interval: 1.15-8.67, P = .025). In conclusion, among patients with CAD undergoing PCI, BMCI was a predictor for cardiovascular events. Further research is required to determine whether medical interventions for BMC can improve patient prognosis.