Raman spectroscopy at the beginning of the twenty‐first century

Schmitt, Michael; Popp, Jürgen

doi:10.1002/jrs.1486

Cited by 170 publications

(125 citation statements)

References 58 publications

Supporting

Mentioning

122

Contrasting

Unclassified

Order By: Relevance

“…energy shifts and phase shifts in our model can, in reality, be caused by a number of coupling mechanisms that exist in molecules, e.g., Stark effect, strong coupling of near-resonant electronic states, or Raman coupling of vibrational states (38)(39)(40)(41)(42)(43)(44)(45). Typically, the higher the pulse energy, the stronger are the energy shifts and, hence, the larger are the phase shifts of the dipole responses (see Eq.…”

Section: Numerical Model and Discussionmentioning

confidence: 99%

Signatures and control of strong-field dynamics in a complex system

Meyer

Liu

Müller

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Controlling chemical reactions by light, i.e., the selective making and breaking of chemical bonds in a desired way with strong-field lasers, is a long-held dream in science. An essential step toward achieving this goal is to understand the interactions of atomic and molecular systems with intense laser light. The main focus of experiments that were performed thus far was on quantum-state population changes. Phase-shaped laser pulses were used to control the population of final states, also, by making use of quantum interference of different pathways. However, the quantum-mechanical phase of these final states, governing the system's response and thus the subsequent temporal evolution and dynamics of the system, was not systematically analyzed. Here, we demonstrate a generalized phase-control concept for complex systems in the liquid phase. In this scheme, the intensity of a control laser pulse acts as a control knob to manipulate the quantum-mechanical phase evolution of excited states. This control manifests itself in the phase of the molecule's dipole response accessible via its absorption spectrum. As reported here, the shape of a broad molecular absorption band is significantly modified for laser pulse intensities ranging from the weak perturbative to the strongfield regime. This generalized phase-control concept provides a powerful tool to interpret and understand the strong-field dynamics and control of large molecules in external pulsed laser fields. C an we find universal concepts to understand and control the response of atoms and molecules in interactions with strong laser fields? This question is at the heart of a vast number of experiments in time-resolved spectroscopy (1-30). The wide range of light sources spanning the spectral range from the X-ray (e.g., free-electron laser sources, synchrotrons) over the visible (conventional laser systems) to the far-infrared regime and covering the temporal range from nanosecond down to attosecond time scales created a wealth of new physics insight into quantum mechanisms, however mostly of simple systems in the gas phase (1-4). In chemistry, the generation of femtosecond laser pulses enabled the investigation of wave packet dynamics in molecules, as the induced vibrations occur on these time scales. Experiments focusing on, for instance, dissociation reactions, atom transfer, isomerization, or solvation dynamics have led to a deeper understanding of chemical bonds and their breakage dynamics and have opened and established the field of femtochemistry (5, 6). The aim is not only to study the light−matter interaction, but to use the obtained understanding of the processes to control the dynamics in complex molecules and, in the future, even to be able to control chemical reactions (7-10). Shaping the amplitude and phase of femtosecond laser pulses has been used, for example, to control the shape of wavefunctions in atomic systems (11) or to control and optimize the single-photon and multiphoton fluorescence in atoms such as cesium (12) and complex systems, e.g....

show abstract

Section: Numerical Model and Discussionmentioning

confidence: 99%

Signatures and control of strong-field dynamics in a complex system

Meyer

Liu

Müller

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Raman spectroscopy is a remarkable analytical technique applicable to almost all disciplines of natural sciences, since it is a non-destructive technique and only requires minimal or no sample preparation [16]. It has several applications in chemistry, physics and biology, highlighting studies on the composition of materials in different areas, such as microbiology, arts, archaeology, geology and atmospheric sciences, among many others [17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Handheld Raman Spectroscopy for the Distinction of Essential Oils Used in the Cosmetics Industry

Jentzsch

Ramos²,

Ciobotă³

2015

Cosmetics

View full text Add to dashboard Cite

Essential oils are highly appreciated by the cosmetics industry because they have antimicrobial and antioxidant properties, among others. Since essential oils are natural products, their inclusion in cosmetic formulations is a common practice. Currently, low-quality and/or adulterated essential oils can be found on the market; therefore, analytical methods for control are required. Raman spectroscopy is a versatile technique that can be used for quality control tasks; the portability of modern devices expand the analytical possibilities also to in situ measurements. Fifteen essential oils of interest for the cosmetics industry were measured using a handheld Raman spectrometer, and the assignment of the main bands observed in their average spectra was proposed. In most cases, it is possible to distinguish the essential oils by a simple visual inspection of their characteristic Raman bands. However, for essential oils extracted from closely-related vegetable species and containing the same main component in a very high proportion, the visual inspection of the spectra may be not enough, and the application of chemometric methods is suggested. Characteristic Raman bands for each essential oil can be used to both identify the essential oils and detect adulterations. OPEN ACCESSCosmetics 2015, 2 163

show abstract

“…Raman spectroscopy [1] is one such technique that provides fundamental knowledge on a molecu lar level and does not require chemical treatment of the sample (contrary to the case, for example, in fluorescence and electron microscopy). It has become an important analyt ical technique for nondestructive, qualitative, and quantitative analysis of materials.…”

Section: Introductionmentioning

confidence: 99%

Raman Spectroscopic Characterization of Wood and Pulp Fibers

Agarwal

2008

Characterization of Lignocellulosic Materials

View full text Add to dashboard Cite

This chapter reviews applications of Raman spectroscopy in the field of wood and pulp fibers. Most of the literature examined was published between 1998 and 2006. In addi tion to introduction, this chapter contains sections on wood and components, mechanical pulp, chemical pulp, modified/treated wood, cellulose I crystallinity of wood fibers, and the "self-absorption" phenomenon in near-infrared (IR) Fourier-transform (FT)-Raman spectroscopy. When needed, the sections are further categorized into various subsections. For example, the section on wood and components contains a variety of topics ranging from Raman band assignments to molecular changes during tensile deformation. From this review it will become clear that Raman spectroscopy has become an essential analytical technique in the field of wood and pulp fibers. IntroductionTechniques that can provide information on the chemical constitution of wood and pulp fibers and on processing-related changes of these materials are of great interest. Raman spectroscopy [1] is one such technique that provides fundamental knowledge on a molecu lar level and does not require chemical treatment of the sample (contrary to the case, for example, in fluorescence and electron microscopy). It has become an important analyt ical technique for nondestructive, qualitative, and quantitative analysis of materials. The technique is useful in a number of areas, including analytical measurements, mechan istic studies, and structural determinations. Studying a sample is very simple and usually involves sampling an area of interest by directing a laser excitation beam and analyzing the collected molecularly specific scattered light [2]. Although initially, obtaining good-quality Raman data required operator skill and training, this has started to change as a result of the commercial availability of compact, easy-to-use, integrated instruments at reasonable cost.Nevertheless, although the specificity of Raman spectroscopy is very high, its sensitivity is somewhat poor. Considering that only a small number of the incident laser photons are inelastically scattered, the detection of analytes present in very low concentrations is limited. To overcome this problem, special Raman signal-enhancing techniques can be applied. The two most prominent approaches are the resonance Raman effect [3] and the

show abstract

Raman spectroscopy at the beginning of the twenty‐first century

Cited by 170 publications

References 58 publications

Signatures and control of strong-field dynamics in a complex system

Signatures and control of strong-field dynamics in a complex system

Handheld Raman Spectroscopy for the Distinction of Essential Oils Used in the Cosmetics Industry

Raman Spectroscopic Characterization of Wood and Pulp Fibers

Contact Info

Product

Resources

About