Predicting Boar Sperm Survival during Liquid Storage Using Vibrational Spectroscopic Techniques.

Artificial insemination (AI) plays a critical role in livestock reproduction, with semen quality being essential. In swine, AI primarily uses cool-stored semen adhering to industry standards assessed through routine analysis, yet fertility inconsistencies highlight the need for enhanced semen evaluation. Over 10-day storage at 17 °C, boar semen samples were analyzed for motility, morphology, sperm membrane integrity, apoptosis, and oxidative stress indicators.

Distinguishing Resonant from Non-Resonant Nonlinear Optical Processes Using Intensity-Intensity Correlation Analyses.

Three-color coherent anti-Stokes Raman scattering (CARS) represents non-degenerate four wave mixing that includes both non-resonant and resonant processes, the contributions of which depend upon how the molecular vibrational modes are being excited by the input laser pulses. The scattering signal due to resonant processes builds up progressively. An advanced analytical tool to reveal this deferred resonant signal buildup phenomenon is in need.

Coherent Anti-Stokes-Stokes Raman Cross-Correlation Spectroscopy: Asymmetric Frequency Shifts in Hydrogen-Bonded Pyridine-Water Complexes.

Hydrogen bonding is a vital molecular interaction for bio-molecular systems, yet deep understanding of its ways of creating various complexes requires extensive empirical testing. A hybrid femtosecond/picosecond coherent Raman spectroscopic technique is applied to study pyridine-water complexes. Both the coherent Stokes and anti-Stokes Raman spectra are recorded simultaneously as the concentration of water in pyridine varied.

In vivo diagnostics of early abiotic plant stress response via Raman spectroscopy.

Development of a phenotyping platform capable of noninvasive biochemical sensing could offer researchers, breeders, and producers a tool for precise response detection. In particular, the ability to measure plant stress in vivo responses is becoming increasingly important. In this work, a Raman spectroscopic technique is developed for high-throughput stress phenotyping of plants.

Temporal coherent control of superfluorescent pulses.

We demonstrate that collective atomic interferences can be investigated by measuring the superfluorescence (SF) time delay. A pair of broadband (≈20  nm), ultrashort (≈80  fs), collinear pulses with a variable delay coherently excites rubidium (Rb) atoms. The generated superfluorescent pulses at 420 nm on the cascade transition are recorded by a picosecond streak camera.

Third and fifth harmonic generation by tightly focused femtosecond pulses at 2.2 μm wavelength in air.

We report experiments on the generation of third and fifth harmonics of millijoule-level, tightly focused, femtosecond laser pulses at 2.2 μm wavelength in air. The measured ratio of yields of the third and fifth harmonics in our setup is found equal to 2 · 10(-4).

Propagation of femtosecond laser pulses through water in the linear absorption regime.

We investigate the controversy regarding violations of the Bouguer-Lambert-Beer (BLB) law for ultrashort laser pulses propagating through water. By working at sufficiently low incident laser intensities, we make sure that any nonlinear component in the response of the medium is negligible. We measure the transmitted power and spectrum as functions of water cell length in an effort to confirm or disprove alleged deviations from the BLB law.

Single-shot detection of bacterial endospores via coherent Raman spectroscopy.

Recent advances in coherent Raman spectroscopy hold exciting promise for many potential applications. For example, a technique, mitigating the nonresonant four-wave-mixing noise while maximizing the Raman-resonant signal, has been developed and applied to the problem of real-time detection of bacterial endospores. After a brief review of the technique essentials, we show how extensions of our earlier experimental work [Pestov D, et al.

Coherent versus incoherent Raman scattering: molecular coherence excitation and measurement.

We present a comparative analysis of spontaneous and coherent Raman scattering on pyridine. The instantaneous excitation of the molecular coherence is done by a pair of ultrashort preparation pulses. Then, a long narrowband probe pulse is scattered off the molecular vibrations.

Optimizing the laser-pulse configuration for coherent Raman spectroscopy.

We introduce a hybrid technique that combines the robustness of frequency-resolved coherent anti-Stokes Raman scattering (CARS) with the advantages of time-resolved CARS spectroscopy. Instantaneous coherent broadband excitation of several characteristic molecular vibrations and the subsequent probing of these vibrations by an optimally shaped time-delayed narrowband laser pulse help to suppress the nonresonant background and to retrieve the species-specific signal. We used this technique for coherent Raman spectroscopy of sodium dipicolinate powder, which is similar to calcium dipicolinate (a marker molecule for bacterial endospores, such as Bacillus subtilis and Bacillus anthracis), and we demonstrated a rapid and highly specific detection scheme that works even in the presence of multiple scattering.