Nuclear Magnetic Resonance Apparatus Research Articles

Nonequilibrium fluctuations of a quantum heat engine

The thermodynamic properties of quantum heat engines are stochastic owing to the presence of thermal and quantum fluctuations. We here experimentally investigate the efficiency and nonequilibrium entropy production statistics of a spin-1/2 quantum Otto cycle in a nuclear magnetic resonance setup. We first study the correlations between work and heat within a cycle by extracting their joint distribution for different driving times. We show that near perfect correlation, corresponding to the tight-coupling condition between work and heat, can be achieved. In this limit, the reconstructed efficiency distribution is peaked at the deterministic thermodynamic efficiency, and fluctuations are strongly suppressed. We further successfully test the second law in the form of a joint fluctuation relation for work and heat in the quantum cycle. Our results characterize the statistical features of a small-scale thermal machine in the quantum domain, and provide means to control them.

Freezing‐Thawing Hysteretic Behavior of Soils

AbstractThe soil freezing characteristic curve (SFCC) plays a crucial role in investigating the soil freezing‐thawing process. Due to the challenges associated with measuring the SFCC, there is a shortage of high‐quality or rigorous test results with sufficient metadata to be effectively used for applications. Current researchers typically conduct freezing tests to measure the SFCC and assume a singular SFCC when studying the freezing‐thawing process of soils, although limited studies indicated that there is a hysteresis during the freezing and thawing process. In this paper, a series of freezing‐thawing tests were performed to assess the SFCC, utilizing a precise nuclear magnetic resonance apparatus. The test results reveal a hysteresis between the SFCC obtained from the freezing process and that from the thawing process. Through analyzing the test results, the hysteresis mechanism of the SFCC is attributed to supercooling. Supercooling inhibits initial pore ice formation during freezing, causing a drastic liquid water‐ice phase change once supercooling ends. Despite being considered closely related, the hysteresis of the SFCC differs from the soil water characteristic curve (SWCC), and the models used to simulate the hysteresis of SWCC cannot directly be used. To address the impact of supercooling on soil freezing‐thawing hysteresis, a novel theoretical model is proposed. Comparisons between the measured and predicted results affirm the validity of the proposed model.

Analyzing the Microscopic Production Characteristics of CO2 Flooding after Water Flooding in Tight Oil Sandstone Reservoirs Utilizing NMR and Microscopic Visualization Apparatus

The microscopic pore structure of tight sandstone reservoirs significantly influences the characteristics of CO2 flooding after water flooding. This research was conducted using various techniques such as casting thin sections, high-pressure mercury injection, scanning electron microscopy, nuclear magnetic resonance (NMR) testing, and a self-designed high-temperature and high-pressure microscopic visualization displacement system. Three types of cores with different pore structures were selected for the flooding experiments and the microscopic visualization displacement experiments, including CO2 immiscible flooding, near-miscible flooding, and miscible flooding after conventional water flooding. The characteristics of CO2 flooding and the residual oil distribution after water flooding were quantitatively analyzed and evaluated. The results show the following: (1) During the water flooding process, the oil produced from type I and type III samples mainly comes from large and some medium pores. Oil utilization of all pores is significant for type II samples. The physical properties and pore types have a greater impact on water flooding. Type I and II samples are more suitable for near-miscible flooding after water flooding. Type III samples are more suitable for miscible flooding after water flooding. (2) In CO2 flooding, oil recovery increases gradually with increasing pressure for all three types of samples. Type II core samples have the highest recovery. Before miscibility, the oil recovered from type I and type II samples is primarily from large pores; however, oil recovery mainly comes from medium pores when reaching miscibility. As for the type III samples, the oil produced in the immiscible state mainly comes from large and medium pores, and the enhanced oil recovery mainly comes from medium and small pores after reaching the near-miscible phase. (3) It can be seen from the microscopic residual oil distribution that oil recovery will increase as the petrophysical properties of the rock model improve. The oil recovery rate of near-miscible flooding after water flooding using the type II model is up to 68.11%. The oil recovery of miscible flooding after water flooding with the type III model is the highest at 74.57%. With increasing pressure, the proportion of flake residual oil gradually decreases, while the proportion of droplet-like and film-like residual oil gradually increases. Type II samples have a relatively large percentage of reticulated residual oil in the near-miscible stage.

Preparation of ultracold ions in strong magnetic field and application to gas-phase NMR spectroscopy II

This paper presents a gas-phase nuclear magnetic resonance (NMR) apparatus, which may enable a tandem combination with an ion cyclotron resonance mass spectrometer. The NMR technique is widely used for analyzing the physical and chemical properties of materials; however, it is mostly limited to materials in condensed phases. Here, we construct a gas-phase NMR apparatus to extend this technique to gas-phase molecular ions. We outline the principle of NMR detection based on a Stern-Gerlach-type experiment and describe the experimental procedures and results for the preparation and manipulation of ultracold ions, which are fundamental for the proposed NMR detection. The development of the gas-phase NMR probe and radio-frequency excitation system and the features of the apparatus are presented. We also discuss the feasibility of combining this apparatus with an ion cyclotron resonance cell for realizing an NMR apparatus for mass-selected molecular ions briefly.

Construction of an active humidity regulation setup for NMR/MRI-Observation and simulation of the controlled evaporation of sessile water droplets

Controlling and improving processes like for example the production of organic semiconductors via printing depends on understanding the interplay of wetting and evaporation of complex fluids. Therefore, examination of the time dependent composition of complex fluid droplets during wetting or evaporation is of interest. The evaporation rate of sessile droplets containing largely water depends on the vapor pressures of the individual components and on the humidity (or partial pressure) of the surrounding gas phase. Hence, for a complete picture of an evaporation process and the comparability of the results of different measurements, it is essential to measure and control the humidity and temperature in the measurement compartment. Accordingly, climate chambers are available in different scales to fit a variety of techniques like contact angle goniometry to obtain results in a controlled atmosphere. We recently reported the application of MRI (Magnetic Resonance Imaging) and spatially resolved NMR (Nuclear Magnetic Resonance) spectroscopy for the examination of the evaporation of sessile droplets on surfaces in 10 mm NMR tubes. These are considered to be closed compartments. Here, we present an apparatus to a) measure and b) control the relative humidity within the sample compartment of the NMR setup by introducing preconditioned gas into the NMR tube. We monitored the evaporation of water droplets using RARE images and compared the volume decay with a) a simple diffusive evaporation model and b) with detailed FEM (finite element numerical model) simulations using COMSOL for validation. We find three evaporation regimes depending on the flow rate as well as on the distance of the gas outlet and the evaporating droplet. In one of the sample configurations tested the evaporation takes place in such a way that it can be described with the help of the simple diffusive model without convection. Thus, the presented approach opens comparative measurements with other methods as well as the observation of droplet evaporation in very dry or very humid environments with and without the influence of convection. Finally, using PRESS spectra, it is shown that the evaporation rate of water from a water/DMSO droplet can be controlled. This shows how the setup presented here can be used to study the evaporation of droplets of more complex mixtures.

Real-Time Monitoring of Pore-Fracture Structure Evolution during Coal Creep Based on NMR

Understanding the structural change of coals at micro- and mesoscales during the creep process is essential for exploring the time-dependent properties of deep coal and the long-term safe and effective operation of deep underground engineering. The conventional triaxial compression and creep tests on coal are carried out using a nuclear magnetic resonance (NMR) apparatus with a complete mechanical loading system at different confining pressures. The variations of parameters such as peak areas of various pore distributions, pore percentage, and porosity increment are quantitatively analyzed by real-time monitoring of T2 spectra during loading. Combined with nuclear magnetic resonance imaging (NMRI), accurate characterization and visualization of microscopic pore structures in coal are realized. The experimental results show that the adsorption pore proportion in the pore structure of the deep coal sample from Pingdingshan, Henan Province, is more than 80%. The changes in seepage pores and microfractures are most obvious in the triaxial compression and creep test. The creep deformation leads to the development of pore structure, and the creep porosity growth rate M increases gradually with increasing stress levels. M can accurately describe the rapid development of the pore structure and the damage accumulation due to time effects during creep. During creep, the most obvious changes in pore structure are the first and last levels of creep. The fractal dimension shows an “inverted V” trend during creep and is more sensitive to the inhibition of pore-fracture structure evolution due to increasing confining pressure. The creep strain increment and porosity increment during graded creep appear to be a similar behavior, indicating that the change of pore structure in the creep process based on the NMR system test can reveal the creep damage mechanism and indirectly characterize the deformation behavior of coal creep.

Understanding Redox Reaction Mechanisms of a Flavin Mononucleotide By in Situ NMR and EPR Techniques

There are many types of energy storage technologies available at present, such as batteries and supercapacitors.1,2 Common battery chemistries include lead3 and lithium-ion4; however, scaling them up to the grid level is challenging.2 Recently, redox flow batteries (RFBs) have attracted much attention, as they can overcome the intermittent nature of renewable energy sources. We have previously developed a new approach to study RFBs by using in-situ nuclear magnetic resonance (NMR) and in-situ electron paramagnetic resonance (EPR), allowing the real time tracking of the redox state of various species in a system. As a result of this work, the electrochemical processes can be better understood. Investigating and understanding the electrolyte properties is a major goal in flow battery research and this will help to develop further RFB systems.Here, we report the analysis of the redox mechanism of a flavin mononucleotide-based anolyte (FMN) in a RFB system with the in-situ NMR and EPR setups. It represents one of the safest families of organic molecules for flow battery applications as it is a molecule derived from riboflavin (vitamin B2) and commonly used as an orange-red food additive.5–7 Nevertheless, the redox properties of flavins in strongly alkaline solution have yet to be thoroughly studied. In particular, the mechanism of the redox reaction for this system is not well understood.To understand the chemistry of FMN in strongly alkaline solution, first the NMR properties were studied. It was revealed that the chemical structure of FMN changed over time, i.e., additional signals were observed to grow in, and, additionally, the existence of a paramagnetic species was confirmed. The paramagnetic species formed on dissolution and was responsible for significant line broadening in the NMR spectrum. To examine how these changes affect the redox properties of FMN, a RFB was cycled over multiple cycles. Here we observed a second charge plateau developed as we continued to cycle the battery that was not mirrored during discharge. The in-situ EPR and NMR analysis reveal that the second plateau was likely caused by a side product derived from FMN. Therefore, possible degradation mechanisms of flavins, such as hydrolysis, need to be considered. Herein we propose that the observed changes over time are caused by the hydrolysis of FMN and provide an explanation for the different redox properties.References Wang, Y. & Zhong, W. H. Development Of Electrolytes Towards Achieving Safe And High-Performance Energy-Storage Devices: A Review. ChemElectroChem 2, 22–36 (2015).Divya, K. C. & Østergaard, J. Battery Energy Storage Technology For Power Systems - An Overview. Electr. Power Syst. Res. 79, 511–520 (2009).Ruetschi, P. Review On The Lead-Acid Battery Science And Technology. J. Power Sources 2, 3–120 (1977).Goodenough, J. B. & Park, K. S. The Li-Ion Rechargeable Battery: A Perspective. J. Am. Chem. Soc. 135, 1167–1176 (2013).Orita, A., Verde, M. G., Sakai, M. & Meng, Y. S. A Biomimetic Redox Flow Battery Based On Flavin Mononucleotide. Nat. Commun. 7, 1–8 (2016).Grajek, H., Zurkowska, G., Drabent, R. & Bojarski, C. Hanna Grajek. Biochem. Biophys. Acta 881, 241–247 (1986).Grajek, H., Drabent, R., Zurkowska, G. & Bojarski, C. Absorption Of The Flavin Dimers. BBA - Gen. Subj. 801, 456–460 (1984). Figure 1

A nuclear quadrupolar spin quantum heat engine

We give an implementable scheme which uses intrinsic quadrupolar nuclear spin interactions to harvest efficient energy from a quantum Otto cycle. We employ realistic parameter regimes for the 23Na nucleus in sodium nitrate. The processes of the cycle are accomplished by orienting the sample with respect to the static magnetic field. The effects of stroke duration on the work output and efficiency are revealed in detail. Finite-time adiabatic transformations leading to quantum friction are found to substantially reduce cycle outputs which are stimulated from the non-secular parts of the quadrupolar interaction. An estimation for the power output at maximum efficiency is also given. We show that with the precise control and manipulation of the intrinsic nuclear spin interactions, for example in an advanced nuclear magnetic resonance setup, makes our scheme implement as a powerful quantum Otto cycle.

Minimum miscibility pressure of CO2 and oil evaluated using MRI and NMR measurements

The minimum miscibility pressure (MMP) between CO2 and crude oil is a critical parameter for CO2 enhanced oil recovery (EOR). Whilst different methodologies have been employed to determine MMP, these methods are either time-consuming or unable to be executed in the actual rock core samples from the relevant reservoir and as such, do not directly consider any accompanying kinetic effects. Here we consider a range of nuclear magnetic resonance (NMR) measurement techniques performed on a benchtop NMR apparatus in terms of their ability to estimate MMP; specifically 1D imaging, self-diffusion measurements and T1/T2 relaxation measurements. Such MMP measurements were performed on two model oils (decane and hexadecane), allowing for validation against comparable MMP literature data, and a local crude oil sample – in this case the results were compared against a PVT measurement performed using a high-pressure variable volume cell (VVC). Reasonably good agreement with these alternative sources of MMP data were realized via NMR measurements of self-diffusion; these provided consistent estimates of MMP for a wider range of oils when compared to 1D imaging and NMR relaxation measurements. NMR T2 measurements however performed equivalently to self-diffusion measurements for higher viscosity fluids based on the limited number of samples studied; such measurements require much simpler NMR hardware and are more readily accessible in both the laboratory and in the field.

Microscopic mechanism analysis of calcareous sand in electrolysis desaturation using 1H L-F NMR

Electrolysis desaturation is a novel method to improve the liquefaction resistance of liquefiable foundations. The microscopic mechanism of the horizontal-layered electrolysis desaturation of calcareous sand specimens was revealed using a low-field nuclear magnetic resonance (1H L-F NMR) apparatus. The expansion and recovery of sand pores was detected, and variation pattern of saturation distribution was explored, as well as the generation and migration of gas bubbles. The test results show that the electrolysis mainly discharged free water from the specimen, and the content of bound water or mechanical bound water kept basically unchanged. The rapid generation of the bubbles could lead to the expansion of the sand pores. Within 3 h after stopping electrolysis, the macropores in the calcareous sand essentially returned to the initial state, and the expansion of micropores and mesopores also remained basically stable. The construction method of prolonged low-current electrolysis or short-time multiple electrolysis could be applied for on-site desaturated foundation treatment. The shape and size of the bubbles produced by electrolysis were related to the calcareous sand pores. The migration of gas after stopping electrolysis was mainly in the vertically upward direction, resulting in the fusion of bubbles and the formation of larger bubbles.

Portable single-sided NMR measurements at variable temperatures: Implementation of a thermo-controlled device and application to the heating of bread dough.

A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample.

Experimental Validation of Fully Quantum Fluctuation Theorems Using Dynamic Bayesian Networks.

Fluctuation theorems are fundamental extensions of the second law of thermodynamics for small systems. Their general validity arbitrarily far from equilibrium makes them invaluable in nonequilibrium physics. So far, experimental studies of quantum fluctuation relations do not account for quantum correlations and quantum coherence, two essential quantum properties. We here apply a novel dynamic Bayesian network approach to experimentally test detailed and integral fully quantum fluctuation theorems for heat exchange between two quantum-correlated thermal spins-1/2 in a nuclear magnetic resonance setup. We concretely verify individual integral fluctuation relations for quantum correlations and quantum coherence, as well as for the sum of all quantum contributions. We further investigate the thermodynamic cost of creating correlations and coherence.

Quantification and division of unfrozen water content during the freezing process and the influence of soil properties by low-field nuclear magnetic resonance

In this study, a low-field nuclear magnetic resonance (NMR) apparatus with the ability to adjust sample temperatures was used to measure the unfrozen water content of frozen soils sampled from the Qinghai-Tibet Plateau. Based on low-field NMR theory, two cutoff values were proposed to quantitatively identify three types of unfrozen water (bulk, capillary, and bound water) in the frozen soils. The influences of soil properties (the clay content, particle size distribution, and clay mineral content) on these three different types of unfrozen water during the soil freezing process were analyzed. The results showed that the soil-freezing characteristic curve of unfrozen water could be divided into three stages, namely, the unfrozen, the rapid-drop, and the residual stages. In the rapid-drop stage, the unfrozen bound water content increases gradually with the increasing clay or clay mineral content, and at a certain temperature, the unfrozen capillary water content increases as the sand and silt content increases. A published power function model is then used to fit the measured data in this study. We found that the single parameter related to soil properties in this model could not sufficiently reflect the influence of clay mineral content or clay content on unfrozen water content.

Easy Access to Energy Fluctuations in Nonequilibrium Quantum Many-Body Systems.

We combine theoretical and experimental efforts to propose a method for studying energy fluctuations, in particular, to obtain the related bistochastic matrix of transition probabilities by means of simple measurements at the end of a protocol that drives a many-body quantum system out of equilibrium. This scheme is integrated with numerical optimizations in order to ensure a proper analysis of the experimental data, leading to physical probabilities. The method is experimentally evaluated employing a two interacting spin-1/2 system in a nuclear magnetic resonance setup. We show how to recover the transition probabilities using only local measures, which enables an experimental verification of the detailed fluctuation theorem in a many-body system driven out of equilibrium.

Quantum Irreversibility in a Misaligned Spin System

A single spin that is misaligned with respect to the static external magnetic field is investigated as a toy model to clarify the nature of irreversibility in terms of inner friction and irreversible work. The coherence generation and the effects of unwanted transitions are analyzed in detail. The behavior of inner friction and irreversible work as a function of protocol time are analyzed for a finite-time unitary transformation. The coherence generation is shown to be the common sign for the inner friction and irreversible work. The excess energy sourced by the unwanted transitions for a quasistatic transformation is found to be the only sign for irreversible work. The angle The angle dependencies of the inner friction and irreversible work are also analyzed explicitly. The selected model and the considered realistic parameters are available to be implemented for the finite-time operations on the nuclear magnetic resonance setups.

Detection of 1H NMR signal in a trapped magnetic field of a compact tubular MgB2 superconductor bulk

We measured 1H nuclear magnetic resonance (NMR) spectra from silicon rubber in a magnetic field trapped by a compact tubular MgB2 superconductor bulk magnet (60 mm outer diameter, 40 mm inner diameter, and 60 mm height) which was magnetized by field-cooled magnetization from an applied field, , of 0.4778 T at 20 K. The sharpest 1H NMR spectrum of the resonant frequency, , of 20.314 MHz, which corresponded to a field strength of 0.4771 T, was observed at 1 mm below the center of the bore of the MgB2 tube. The homogeneity of the trapped field was within 100 ppm between z −2 and +2 mm along the central z-axis, which was evaluated by the position-dependent . No change in the trapped field was observed for about 25 d, which corresponded to a decay rate of less than 0.1 ppb h−1. The obtained results suggest that the MgB2 bulk magnet is a promising candidate for a magnetic pole in an NMR apparatus.

An electrochemical cell for in operando 13C nuclear magnetic resonance investigations of carbon dioxide/carbonate processes in aqueous solution.

In operando nuclear magnetic resonance (NMR) spectroscopy is one method for the online investigation of electrochemical systems and reactions. It allows for real-time observations of the formation of products and intermediates, and it grants insights into the interactions of substrates and catalysts. An in operando NMR setup for the investigation of the electrolytic reduction of at silver electrodes has been developed. The electrolysis cell consists of a three-electrode setup using a working electrode of pristine silver, a chlorinated silver wire as the reference electrode, and a graphite counter electrode. The setup can be adjusted for the use of different electrode materials and fits inside a 5 mm NMR tube. Additionally, a shielding setup was employed to minimize noise caused by interference of external radio frequency (RF) waves with the conductive components of the setup. The electrochemical performance of the in operando electrolysis setup is compared with a standard electrolysis cell. The small cell geometry impedes the release of gaseous products, and thus it is primarily suited for current densities below 1 mA cm. The effect of conductive components on CNMR experiments was studied using a -saturated solution of aqueous bicarbonate electrolyte. Despite the field distortions caused by the electrodes, a proper shimming could be attained, and line widths of ca. 1 Hz were achieved. This enables investigations in the sub-Hertz range by NMR spectroscopy. High-resolution CNMR and relaxation time measurements proved to be sensitive to changes in the sample. It was found that the dynamics of the bicarbonate electrolyte varies not only due to interactions with the silver electrode, which leads to the formation of an electrical double layer and catalyzes the exchange reaction between and , but also due to interactions with the electrochemical setup. This highlights the necessity of a step-by-step experiment design for a mechanistic understanding of processes occurring during electrochemical reduction.

Magnetic Moments of Short-Lived Nuclei with Part-per-Million Accuracy: Toward Novel Applications of β -Detected NMR in Physics, Chemistry, and Biology

We determine for the first time the magnetic dipole moment of a short-lived nucleus with part-per-million (ppm) accuracy. To achieve this two orders of magnitude improvement over previous studies, we implement a number of innovations into our $\beta$-detected Nuclear Magnetic Resonance ($\beta$-NMR) setup at ISOLDE/CERN. Using liquid samples as hosts we obtain narrow, sub-kHz linewidth, resonances, while a simultaneous in-situ $^1$H NMR measurement allows us to calibrate and stabilize the magnetic field to ppm precision, thus eliminating the need for additional $\beta$-NMR reference measurements. Furthermore, we use ab initio calculations of NMR shielding constants to improve the accuracy of the reference magnetic moment, thus removing a large systematic error. We demonstrate the potential of this combined approach with the 1.1 s half-life radioactive nucleus $^{26}$Na, which is relevant for biochemical studies. Our technique can be readily extended to other isotopic chains, providing accurate magnetic moments for many short-lived nuclei. Furthermore, we discuss how our approach can open the path towards a wide range of applications of the ultra-sensitive $\beta$-NMR in physics, chemistry, and biology.

Cl- and Na+ ions binding in slag and fly ash cement paste during early hydration as studied by 1H, 35Cl and 23Na NMR

Lacking effective and in particular direct methods, the study on Cl- and Na+ ion binding during hydration has rarely been reported. In this study, a specially developed Nuclear Magnetic Resonance setup was employed to study the Cl- and Na+ ion binding of cement pastes during hydration. Influence factors, such as slag and fly ash replacement, on the 1H, 35Cl and 23Na relaxation of the cement paste made with 1 mol/L NaCl solutions were investigated. It was found that the increase of slag in the cement gives rise to bigger pores during hydration, and the fly ash resulted in less water being consumed. The Cl- signals would first be stable then gradually decrease as a function of time. The slag in cement has minor impacts on the Cl- ions binding, and the fly ash replacement in the cement would result in less Cl- ions binding during the hydration. Results also suggest that the slag could result in later Na+ binding, and the fly ash in the cement will significantly reduce the Na+ binding. Besides, the Cl- ions will bind earlier compared to the Na+ ions, which is probably related to the characteristics of the hydrates. The normalized 35Cl and 23Na signal intensity, in general, decrease with water consumption reflecting the hydration. Furthermore, the early formed hydrates would consume relatively less water but bind more Cl- and Na- ions.

In situ NMR Investigation of the Photoresponse of Perovskite Crystal

Summary Hybrid perovskites are outstanding candidates for use in optoelectronic devices. Nonetheless, hybrid perovskites present numerous fundamental issues that are not yet fully understood. This study seeks to address this problem by reporting on the occurrence of ultraslow dynamic orientation changes in the methylammonium (MA) cations and the corresponding changes in the inorganic lattice of MAPbI3 perovskite crystals occurring over a time scale of 100 s under continuous illumination based on in situ single-crystal 2H nuclear magnetic resonance and in situ X-ray diffraction results. The demonstrated ultraslow dynamic changes in MAPbI3 are far slower than elementary molecular motions typically having time scales of femtoseconds and picoseconds and have never been reported previously. The ultraslow dynamic changes have been correlated with the reduction of band gap and the increase of absorption coefficient of MAPbI3, providing the molecular origins of the stabilization process in the photoresponse of the MAPbI3 device.