(Press-News.org) Enhanced local electric fields are predominant in nonlinear optical properties, particularly in surface-enhanced Raman scattering (SERS), which is a sensitive technique used for the detection of trace amounts of chemicals. Analysis of the electric fields around nanostructures indicates that they can provide a basic foundation to obtain greater SERS intensity. Professor ZHANG Zhongyue and his group from the College of Physics and Information Technology at Shaanxi Normal University have proposed a novel scheme to enhance the local electric fields around nanostructures. The scheme is based on manipulation of the incident wave to allow the superposition of the electric fields of multiple beams of light to work as the excitation source for the electrons in the nanostructures, and larger electric fields are thus excited around the nanostructures. Their work, entitled "Enhancing the electric fields around the nanorods by using metal grooves", was published in SCIENCE CHINA Physics, Mechanics & Astronomy 2012, vol. 55 (10).
SERS is one of the most promising applications of the enhanced optical fields generated by the excitation of local surface plasmons in metal nanostructures. The SERS spectrum reveals the vibration modes of molecules, thus conveying specific information with fingerprint-level accuracy. Also, the sensitivity of SERS is one of the highest among the currently available analytical techniques, potentially leading to single molecule detection. Although the SERS signal from a particular molecule originates from both chemical and electromagnetic contributions, the dominant factor in SERS is a result of the local electromagnetic field enhancement caused by the resonant excitation of localized surface plasmons in metal nanostructures. Because the surface plasmon resonance depends strongly on the shape of the nanostructures, nanostructures with different topological shapes were prepared to enhance the local electric fields. It was found that nanostructure pairs and nanogalaxies could also achieve stronger electric fields because of the electric field couplings or cascade electric field enhancements in the nanosystems.
Unlike previous methods of building the SERS substrates, ZHANG Zhongyue and his group presented a novel scheme to enhance the electric fields around the nanostructures. By manipulating the incident wave, the superposition of the electric fields of multiple beams of light works as the excitation source. When the phase differences between the multiple beams of light are designed appropriately, the excitation fields for electron oscillations in the nanostructures are much greater than those at normal incidence. The electric fields around these nanostructures are also larger than those at normal incidence. The starting point of this scheme is the enhancement of the excitation field for the electron oscillations in the nanostructures, which does not conflict with previous designs that varied the topological shapes of the nanostructures or combined nanostructures to generate larger electric fields.
Following the previously discussed schemes, ZHANG Zhongyue and his group presented the silver nanorod-groove system for SERS substrates. The grooves are used to manipulate the incident waves. The superposition of the electric fields of multiple beams of light works to excite the electron oscillations in the nanorods. As a result, the electric fields around the nanorods in the nanorod-groove system are much greater than those around individual nanorods and those in the nanorod-film system.
For the nanorod-groove system, even with fabrication defects related to the oblique angle of the groove and the location of the nanorod, numerical calculations also show that larger electric fields can be excited around the nanorods. Although the separation distances between the nanorods affect the electric field distributions, the electric fields are always larger than those around individual nanorods and those around the nanorods in the nanorod-film system. Therefore, the nanorod-groove system provides a good structure to further enhance the local electric fields around the nanorods.
INFORMATION:
See the article: Zhao Y. N., Qin Y., Cao W., et al. Enhancing the electric fields around the nanorods by using metal grooves. SCI CHINA Phys. Mech. Astron., 2012, 55 (10): 1763-1768
A novel scheme to enhance local electric fields around metal nanostructures
2012-10-20
[Attachments] See images for this press release:
ELSE PRESS RELEASES FROM THIS DATE:
AAP president Dr. Robert Block reflects on changes in pediatric health
2012-10-20
NEW ORLEANS – Robert Block, MD, FAAP, outgoing president of the American Academy of Pediatrics (AAP), will address attendees at the AAP National Conference & Exhibition Saturday, Oct. 20, at 10:40 a.m. during the opening plenary session at the Ernest N. Morial Convention Center in New Orleans. Dr. Block will lead a discussion on the "soul of a pediatrician," and how a pediatrician's devotion and compassion for children must persist as the world of medicine changes around us.
Dr. Block will also focus on his yearlong theme of "all adults were once children," to promote ...
American Academy of Pediatrics study documents early puberty onset in boys
2012-10-20
NEW ORLEANS -- A study conducted by the American Academy of Pediatrics (AAP) has documented that boys in the U.S. are experiencing the onset of puberty six months to two years earlier than reported in previous research.
The study, "Secondary Sexual Characteristics in Boys: Data from the Pediatric Research in Office Settings Network," will be published in the November 2012 Pediatrics and published online Oct. 20 to coincide with the AAP National Conference & Exhibition in New Orleans.
The trend toward earlier onset of puberty in girls is now generally accepted and supported ...
Cyberbullying only rarely the sole factor identified in teen suicides
2012-10-20
NEW ORLEANS – Cyberbullying – the use of the Internet, phones or other technologies to repeatedly harass or mistreat peers – is often linked with teen suicide in media reports. However, new research presented on Saturday, Oct. 20, at the American Academy of Pediatrics (AAP) National Conference and Exhibition in New Orleans, shows that the reality is more complex. Most teen suicide victims are bullied both online and in school, and many suicide victims also suffer from depression.
For the abstract, "Cyberbullying and Suicide: A Retrospective Analysis of 41 Cases," researchers ...
In vitro fertilization linked to increase risk for birth defects
2012-10-20
NEW ORLEANS – In vitro fertilization (IVF) may significantly increase the risk of birth defects, particularly those of the eye, heart, reproductive organs and urinary systems, according to new research presented Saturday, Oct. 20, at the American Academy of Pediatrics (AAP) National Conference and Exhibition in New Orleans.
According to the study, despite increasing use of IVF in the United States, associations between birth defects and IVF are poorly understood. Management of birth defects comprises a large part of pediatric surgical care and demands significant health ...
Traffic Accidents Increase as Texas Oil and Gas Industry Grows
2012-10-20
Traffic Accidents Increase as Texas Oil and Gas Industry Grows
Here are some alarming statistics for workers in the busy oil and gas industry in Texas. From 2003 to 2008, the leading cause of death for oil field workers nationwide was highway accidents, according to the U.S. Centers for Disease Control. And in 2010, the U.S. Bureau of Labor Statistics of the U.S. Department of Labor reported that almost 40 percent of fatalities in the oil and gas industry resulted from motor vehicle accidents.
Many Texas communities are currently seeing big increases in traffic volume ...
Arguing Over Money Major Factor in Many New Jersey Divorces
2012-10-20
Arguing Over Money Major Factor in Many New Jersey Divorces
It is not unusual for married couples to have disagreements. Some arguments erupt over trivial issues, and some are the result of major concerns. Those couples who argue about money may be doing more harm to their marriages than they know. Fights about money can lead to divorce. However, people can help minimize fights about money during a divorce with a prenuptial agreement.
Money Arguments Contribute to Divorces
Disagreements about money are the most common reason people argue, according to a study conducted ...
Establishing Child Guardianship in Oklahoma
2012-10-20
Establishing Child Guardianship in Oklahoma
The right to raise one's own child is considered fundamental in the U.S., and authorities will not interfere with the parent-child relationship without a compelling reason. In some cases, parents are unwilling or unable to care for their children and other people step in to help. Oklahoma law recognizes the authority of a person besides a child's parents to raise a child through a guardianship.
What Is a Guardianship?
Under Oklahoma law, the court may appoint a child a guardian "when it appears necessary or convenient." ...
Being Too Nice During an Oklahoma Divorce Can Cause Pain Later
2012-10-20
Being Too Nice During an Oklahoma Divorce Can Cause Pain Later
When couples divorce, many strive to make the split amicable. Whether it be because they need to continue to have a relationship as parents of children from the marriage or they believe a friendly divorcewill be less emotionally taxing, some couples make a concerted effort to maintain a civil, even cordial, tone during the proceedings. However, in the effort to be considerate to a former spouse, a person may inadvertently sabotage his or her chances for financial security after the divorce. Oklahoma residents ...
Mediation Can Benefit Those Going Through Divorce in Connecticut
2012-10-20
Mediation Can Benefit Those Going Through Divorce in Connecticut
Divorce can be a horrible thing, filled with bitter arguments, wounded feelings and protracted court battles. However, more people are realizing the damage that using litigation for divorce can cause and are opting for divorce mediation instead. People in Connecticut considering divorce should be aware of what mediation is and some of the benefits it may offer over going to court for divorce.
Mediation Process
When a couple decides to use mediation for a divorce, they select a mediator trained in ...
Options to Enforce Nursing Home Standards Keep Operators Honest
2012-10-20
Options to Enforce Nursing Home Standards Keep Operators Honest
Nursing home residents in California have a set of rights and when violated those rights should be enforced. A common violation among nursing homes is the failure to meet nurse-staffing standards, and the failure of nursing homes to meet staff requirements can lead to inadequate care, injury or even death. Fortunately, a California appeals court recently ruled that nursing home residents have multiple ways to enforce their rights regarding this violation.
Appellate Ruling Allows Nursing Home Residents ...